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An Introduction to Administration for Social Workers (Routledge Revivals)
by Joyce WarhamFirst Published in 1967, An Introduction to Administration for Social Workers argues that the tasks of social workers in our society cannot be understood without considering the administrative framework within which they work- a new approach requiring much study and research. In this book Joyce Warham examines some of its most important aspects.The book progresses from the theoretical to the practical. Part I presents a background of theories of organization and of management, stressing elements generic to all organizations, and with the object of offering a ‘frame of reference’ for considering the nature of administration. Part II begins with a discussion of the characteristics of social work agencies as distinct from organizations of other kinds and moves on from there to consider the specific function and tasks of the administrator. This is an important introductory volume for students of social work.
An Introduction to Advanced Fluid Dynamics and Fluvial Processes
by B. S. Mazumder T. I. EldhoThis book covers fluid dynamics and fluvial processes, including basics applicable to open channel flow followed by turbulence characteristics related to sediment-laden flows. It presents well-balanced exposure of physical concepts, mathematical treatments, validation of the models/theories, and experimentations using modern electronic gadgets within the scope. In addition, it explores fluid motions, sediment-fluid interactions, erosion and scouring, sediment suspension and bed load transportation, image processing for particle dynamics, and various problems of applied fluid mechanics in natural sciences. Features: Gives comprehensive treatment on fluid dynamics and fluvial process from fundamentals to advanced level applications in one volume. Presents knowledge on sediment transport and its interaction with turbulence. Covers recent methodologies in the study of turbulent flow theories with verification of laboratory data collected by ADV, PIV, URS, LDA, and imaging techniques, and field data collected by MMB and S4 current meters. Explores the latest empirical formulae for the estimations of bed load, saltation, suspension, and bedform migration. Contains theory to experimentations with field practices with comprehensive explanations and illustrations. This book is aimed at senior undergraduates, engineering and applied science postgraduate and research students working in mechanical, civil, geo-sciences, and chemical engineering departments pertaining to fluid mechanics, hydraulics, sediment transportation, and turbulent flows.
An Introduction to Aesthetics (Routledge Library Editions: Aesthetics Ser. #1)
by E. F. CarrittThis book provides an introduction into the subject of aesthetics and the problems associated with it. It emphasizes that aesthetics is not strictly a criterion or rule for production or appreciation. The book will be of interest to students of both art and philosophy.
An Introduction to African Politics
by Alex ThomsonAn Introduction to African Politics is the ideal textbook for those new to the study of this vast and fascinating continent. It makes sense of the diverse political systems that are a feature of Africa by using familiar concepts, chapter by chapter, to examine the continent as a whole. The result is a textbook that identifies the essential features of African politics, allowing students to grasp the recurring political patterns that have dominated this part of the world since independence.Features and benefits of the book include:* thematically organised, with individual chapters exploring issues such as colonialism, ethnicity, nationalism, social class, ideology, legitimacy, sovereignty, and democracy* identifies the key recurrent theme of competitive relationships between the African state, its civil society, and external interests* contains useful boxed case studies of key countries at the end of each chapter, including: Kenya; Tanzania; Nigeria; Botswana; Ivory Coast; Uganda; Somalia; Ghana; Zaire; and Algeria* each chapter concludes with key terms and definitions as well as questions, advice on further reading, and useful notes and references* clearly and accessibly written by an experienced teacher of the subject.
An Introduction to African Politics
by Alex ThomsonThe fourth edition of An Introduction to African Politics is an ideal textbook for those new to the study of this fascinating continent. It gets to the heart of the politics of this part of the world. How is modern Africa still influenced by its colonial past? How do strong ethnic and religious identities on the continent affect government? Why has the military been so influential? How does African democracy differ from democracy in the West? These are the sorts of question tackled by the book. The result is a textbook that identifies the essential features of African politics, allowing students to grasp the recurring political patterns that have dominated this continent since independence. Key features include: Thematically organised, with individual chapters exploring issues such as colonialism, ethnicity, nationalism, religion, social class, ideology, legitimacy, authority, sovereignty and democracy. Identifies key recurrent themes such as the competitive relationships between the African state, its civil society and external interests. Contains useful boxed case studies at the end of each chapter, including: Kenya, Tanzania, Nigeria, Botswana, Côte d'Ivoire, Uganda, Somalia, Ghana, Democratic Republic of the Congo and Zimbabwe. Each chapter concludes with key terms and definitions, as well as questions and advice on further reading. This textbook is essential reading for students seeking an accessible introduction to the complex social relationships and events that characterise the politics of post-colonial Africa.
An Introduction to African Politics
by Alex ThomsonThis fully updated fifth edition of An Introduction to African Politics is an ideal textbook for those new to the study of this fascinating continent. Charting trends in government over six decades of the post-colonial era, the book tackles key questions such as: How have African states made sense of their colonial inheritance? How relevant are ethnic and religious identities? Why have some states collapsed and others prospered? Why did the one-party state fail? Why is contemporary Africa now dominated by electoral authoritarian states, and not the multi-party democracies promised in the 1990s? Key features include: thematically organised, with chapters exploring issues such as colonialism, ethnicity, nationalism, religion, social class, ideology, legitimacy, authority, sovereignty and democracy; new five-part structure makes clearer Africa’s political evolution over time; new chapter on the emergence of ‘hybrid states’ and ‘electoral authoritarianism’; more coverage of twenty-first century governance trends such as China’s impact, the changing role of the military, different uses of ‘client–patron’ networks, Western conditionality and the ‘Africa rising’ debate; colour presentation of maps, photos and data; boxed case studies including Mali, Tanzania, Nigeria, Botswana, Côte d’Ivoire, Uganda, Somalia, Ghana, the Democratic Republic of the Congo, Tunisia and Angola; each chapter concludes with key terms and definitions, questions and further reading. An Introduction to African Politics is essential reading for students seeking an accessible introduction to the complex social relationships and events that characterise the politics of post-colonial Africa.
An Introduction to Agent-Based Modeling: Modeling Natural, Social, and Engineered Complex Systems with NetLogo
by Uri Wilensky William RandThe advent of widespread fast computing has enabled us to work on more complex problems and to build and analyze more complex models. This book provides an introduction to one of the primary methodologies for research in this new field of knowledge. Agent-based modeling (ABM) offers a new way of doing science: by conducting computer-based experiments. ABM is applicable to complex systems embedded in natural, social, and engineered contexts, across domains that range from engineering to ecology. An Introduction to Agent-Based Modeling offers a comprehensive description of the core concepts, methods, and applications of ABM. Its hands-on approach -- with hundreds of examples and exercises using NetLogo -- enables readers to begin constructing models immediately, regardless of experience or discipline.The book first describes the nature and rationale of agent-based modeling, then presents the methodology for designing and building ABMs, and finally discusses how to utilize ABMs to answer complex questions. Features in each chapter include step-by-step guides to developing models in the main text; text boxes with additional information and concepts; end-of-chapter explorations; and references and lists of relevant reading. There is also an accompanying website with all the models and code.
An Introduction to Agent-Based Modeling: Modeling Natural, Social, and Engineered Complex Systems with NetLogo
by Uri Wilensky William RandA comprehensive and hands-on introduction to the core concepts, methods, and applications of agent-based modeling, including detailed NetLogo examples. The advent of widespread fast computing has enabled us to work on more complex problems and to build and analyze more complex models. This book provides an introduction to one of the primary methodologies for research in this new field of knowledge. Agent-based modeling (ABM) offers a new way of doing science: by conducting computer-based experiments. ABM is applicable to complex systems embedded in natural, social, and engineered contexts, across domains that range from engineering to ecology. An Introduction to Agent-Based Modeling offers a comprehensive description of the core concepts, methods, and applications of ABM. Its hands-on approach—with hundreds of examples and exercises using NetLogo—enables readers to begin constructing models immediately, regardless of experience or discipline. The book first describes the nature and rationale of agent-based modeling, then presents the methodology for designing and building ABMs, and finally discusses how to utilize ABMs to answer complex questions. Features in each chapter include step-by-step guides to developing models in the main text; text boxes with additional information and concepts; end-of-chapter explorations; and references and lists of relevant reading. There is also an accompanying website with all the models and code.
An Introduction to Agricultural Geography
by David GriggEmploying nearly half of the world's workforce, agriculture is clearly of great economic and social importance. An incredible variety of methods are used globally; the Western world has the latest scientific and industrial advancements at its disposal, yet in the Thrid World a living is made using tools that have hardly changed in two thousand years. An Introduction to Agricultural Geography provides an extensive guide through this diverse and increaslingly important geographical subject, aiming to show that a wide range of factors explain how agricultural practices differ from place to place. Dealing with the physical environment, economic behaviour and demands, institutional and social influences and the impact of farming upon the environment, the author has produced an important introductory text that is topical, incisive and ultimately essential to reach an understanding of the remarkable diversity of the world's major industry.
An Introduction to Agroforestry: Four Decades of Scientific Developments
by Vimala D. Nair B. Mohan Kumar P. K. NairAgroforestry – the practice of growing trees and crops in interacting combinations – is recognized the world over as an integrated approach to sustainable land-use. Agroforestry systems, being multifunctional, facilitate not only the production of food and wood products but also provide a variety of ecosystem services such as climate-change mitigation, biodiversity conservation, and soil quality improvement. Agroforestry research has made rapid strides since organized efforts started in the late 1970s. Today, a vast body of scientific knowledge and an impressive array of publications on agroforestry are available. Four World Congresses on Agroforestry conducted once every five years since 2004 have brought together the global community of agroforestry professionals and practitioners to share and discuss the emerging trends and paradigm shifts in this field. The fifth Congress is scheduled to be held in Québec, Canada. However, a comprehensive college-level textbook incorporating these research findings did not exist until this book was first published. The first edition of this book in 1993 (Nair, P. K. R., 1993) is out of print and somewhat dated. This revised edition, with emphasis on the scientific developments during the past more than four decades, addresses this long-felt need.
An Introduction to Akkadian Literature: Contexts and Content
by Alan Charles LenziThis book initiates the reader into the study of Akkadian literature from ancient Babylonia and Assyria. With this one relatively short volume, the novice reader will develop the literary competence necessary to read and interpret Akkadian texts in translation and will gain a broad familiarity with the major genres and compositions in the language.The first part of the book presents introductory discussions of major critical issues, organized under four key rubrics: tablets, scribes, compositions, and audiences. Here, the reader will find descriptions of the tablets used as writing material; the training scribes received and the institutional contexts in which they worked; the general characteristics of Akkadian compositions, with an emphasis on poetic and literary features; and the various audiences or users of Akkadian texts. The second part surveys the corpus of Akkadian literature defined inclusively, canvasing a wide spectrum of compositions. Legal codes, historical inscriptions, divinatory compendia, and religious texts have a place in the survey alongside narrative poems, such as the Epic of Gilgamesh, Enuma elish, and Babylonian Theodicy. Extensive footnotes and a generous bibliography guide readers who wish to continue their study.Essential for students of Assyriology, An Introduction to Akkadian Literature will also prove useful to biblical scholars, classicists, Egyptologists, ancient historians, and literary comparativists.
An Introduction to Akkadian Literature: Contexts and Content
by Alan LenziThis book initiates the reader into the study of Akkadian literature from ancient Babylonia and Assyria. With this one relatively short volume, the novice reader will develop the literary competence necessary to read and interpret Akkadian texts in translation and will gain a broad familiarity with the major genres and compositions in the language.The first part of the book presents introductory discussions of major critical issues, organized under four key rubrics: tablets, scribes, compositions, and audiences. Here, the reader will find descriptions of the tablets used as writing material; the training scribes received and the institutional contexts in which they worked; the general characteristics of Akkadian compositions, with an emphasis on poetic and literary features; and the various audiences or users of Akkadian texts. The second part surveys the corpus of Akkadian literature defined inclusively, canvasing a wide spectrum of compositions. Legal codes, historical inscriptions, divinatory compendia, and religious texts have a place in the survey alongside narrative poems, such as the Epic of Gilgamesh, Enuma elish, and Babylonian Theodicy. Extensive footnotes and a generous bibliography guide readers who wish to continue their study.Essential for students of Assyriology, An Introduction to Akkadian Literature will also prove useful to biblical scholars, classicists, Egyptologists, ancient historians, and literary comparativists.
An Introduction to Algebraic Statistics with Tensors (UNITEXT #118)
by Cristiano Bocci Luca ChiantiniThis book provides an introduction to various aspects of Algebraic Statistics with the principal aim of supporting Master’s and PhD students who wish to explore the algebraic point of view regarding recent developments in Statistics. The focus is on the background needed to explore the connections among discrete random variables. The main objects that encode these relations are multilinear matrices, i.e., tensors. The book aims to settle the basis of the correspondence between properties of tensors and their translation in Algebraic Geometry. It is divided into three parts, on Algebraic Statistics, Multilinear Algebra, and Algebraic Geometry. The primary purpose is to describe a bridge between the three theories, so that results and problems in one theory find a natural translation to the others. This task requires, from the statistical point of view, a rather unusual, but algebraically natural, presentation of random variables and their main classical features. The third part of the book can be considered as a short, almost self-contained, introduction to the basic concepts of algebraic varieties, which are part of the fundamental background for all who work in Algebraic Statistics.
An Introduction to Algebraic Structures (Dover Books on Mathematics)
by Joseph LandinAs the author notes in the preface, "The purpose of this book is to acquaint a broad spectrum of students with what is today known as 'abstract algebra.'" Written for a one-semester course, this self-contained text includes numerous examples designed to base the definitions and theorems on experience, to illustrate the theory with concrete examples in familiar contexts, and to give the student extensive computational practice.The first three chapters progress in a relatively leisurely fashion and include abundant detail to make them as comprehensible as possible. Chapter One provides a short course in sets and numbers for students lacking those prerequisites, rendering the book largely self-contained. While Chapters Four and Five are more challenging, they are well within the reach of the serious student.The exercises have been carefully chosen for maximum usefulness. Some are formal and manipulative, illustrating the theory and helping to develop computational skills. Others constitute an integral part of the theory, by asking the student to supply proofs or parts of proofs omitted from the text. Still others stretch mathematical imaginations by calling for both conjectures and proofs.Taken together, text and exercises comprise an excellent introduction to the power and elegance of abstract algebra. Now available in this inexpensive edition, the book is accessible to a wide range of students, who will find it an exceptionally valuable resource.
An Introduction to Algebraic Topology (Dover Books on Mathematics)
by Andrew H. WallaceThis self-contained treatment of algebraic topology assumes only some knowledge of real numbers and real analysis. The first three chapters focus on the basics of point-set topology, offering background to students approaching the subject with no previous knowledge. Readers already familiar with point-set topology can proceed directly to Chapter 4, which examines the fundamental group as well as homology groups and continuous mapping, barycentric subdivision and excision, the homology sequence, and simplicial complexes.Exercises form an integral part of the text; they include theorems that are as valuable as some of those whose proofs are given in full. Author Andrew H. Wallace, Professor Emeritus at the University of Pennsylvania, concludes the text with a guide to further reading.
An Introduction to Algorithmic Trading
by Edward Leshik Jane CralleInterest in algorithmic trading is growing massively - it's cheaper, faster and better to control than standard trading, it enables you to 'pre-think' the market, executing complex math in real time and take the required decisions based on the strategy defined. We are no longer limited by human 'bandwidth'. The cost alone (estimated at 6 cents per share manual, 1 cent per share algorithmic) is a sufficient driver to power the growth of the industry. According to consultant firm, Aite Group LLC, high frequency trading firms alone account for 73% of all US equity trading volume, despite only representing approximately 2% of the total firms operating in the US markets. Algorithmic trading is becoming the industry lifeblood. But it is a secretive industry with few willing to share the secrets of their success.The book begins with a step-by-step guide to algorithmic trading, demystifying this complex subject and providing readers with a specific and usable algorithmic trading knowledge. It provides background information leading to more advanced work by outlining the current trading algorithms, the basics of their design, what they are, how they work, how they are used, their strengths, their weaknesses, where we are now and where we are going.The book then goes on to demonstrate a selection of detailed algorithms including their implementation in the markets. Using actual algorithms that have been used in live trading readers have access to real time trading functionality and can use the never before seen algorithms to trade their own accounts.The markets are complex adaptive systems exhibiting unpredictable behaviour. As the markets evolve algorithmic designers need to be constantly aware of any changes that may impact their work, so for the more adventurous reader there is also a section on how to design trading algorithms.All examples and algorithms are demonstrated in Excel on the accompanying CD ROM, including actual algorithmic examples which have been used in live trading.
An Introduction to America's Music
by Richard Crawford Larry HamberlinRichard Crawford and Larry Hamberlin show how the lively interactions between the folk, popular, and classical spheres have made American music resonate with audiences around the world. Students will learn how to listen critically to eighty-eight pieces in all the major styles and genres, while gaining a clearer understanding of music's role in the history of American society, business, and technology.
An Introduction to America's Music (Third Edition)
by Richard Crawford Larry HamberlinAn ear-opening exploration of music's New World, from Puritan psalmody to Hamilton Authors Richard Crawford and Larry Hamberlin use 90 pieces to show how the lively interactions among the folk, popular, and classical spheres have made American music resonate with audiences around the world. Along the way, students gain a clearer understanding of music's role in the history of American society, business, and technology. This purchase offers access to the digital ebook only.
An Introduction to American Policing (Second Edition)
by Dennis J. StevensAn Introduction to American Policing continues to engage students with a balanced yet critical investigation of police history and theory. This comprehensive text connects the US criminal justice system, criminology, and law enforcement knowledge to the progress of the police community. Updated case studies and narratives from violators along with current research help students understand the central theories and practical realities of American law enforcement. This leading-edge textbook will satisfy both scholars, who lean toward theoretical perspectives, and practitioners, who favor practical recommendations. An Introduction to American Policing, Second Edition is an exciting and modern resource that will challenge and encourage readers to understand, imagine, reflect, and exercise good judgment when thinking about the principal issues related to American policing moving toward 2020.
An Introduction to Analysis (Textbooks in Mathematics)
by James R. KirkwoodThe third edition of this widely popular textbook is authored by a master teacher. This book provides a mathematically rigorous introduction to analysis of realvalued functions of one variable. This intuitive, student-friendly text is written in a manner that will help to ease the transition from primarily computational to primarily theoretical mathematics. The material is presented clearly and as intuitive as possible while maintaining mathematical integrity. The author supplies the ideas of the proof and leaves the write-up as an exercise. The text also states why a step in a proof is the reasonable thing to do and which techniques are recurrent. Examples, while no substitute for a proof, are a valuable tool in helping to develop intuition and are an important feature of this text. Examples can also provide a vivid reminder that what one hopes might be true is not always true. Features of the Third Edition: Begins with a discussion of the axioms of the real number system. The limit is introduced via sequences. Examples motivate what is to come, highlight the need for hypothesis in a theorem, and make abstract ideas more concrete. A new section on the Cantor set and the Cantor function. Additional material on connectedness. Exercises range in difficulty from the routine "getting your feet wet" types of problems to the moderately challenging problems. Topology of the real number system is developed to obtain the familiar properties of continuous functions. Some exercises are devoted to the construction of counterexamples. The author presents the material to make the subject understandable and perhaps exciting to those who are beginning their study of abstract mathematics. Table of Contents Preface Introduction The Real Number System Sequences of Real Numbers Topology of the Real Numbers Continuous Functions Differentiation Integration Series of Real Numbers Sequences and Series of Functions Fourier Series Bibliography Hints and Answers to Selected Exercises Index Biography James R. Kirkwood holds a Ph.D. from University of Virginia. He has authored fifteen, published mathematics textbooks on various topics including calculus, real analysis, mathematical biology and mathematical physics. His original research was in mathematical physics, and he co-authored the seminal paper in a topic now called Kirkwood-Thomas Theory in mathematical physics. During the summer, he teaches real analysis to entering graduate students at the University of Virginia. He has been awarded several National Science Foundation grants. His texts, Elementary Linear Algebra, Linear Algebra, and Markov Processes, are also published by CRC Press.
An Introduction to Analysis of Financial Data With R
by Ruey S. TsayA complete set of statistical tools for beginning financial analysts from a leading authority Written by one of the leading experts on the topic, An Introduction to Analysis of Financial Data with R explores basic concepts of visualization of financial data. Through a fundamental balance between theory and applications, the book supplies readers with an accessible approach to financial econometric models and their applications to real-world empirical research. The author supplies a hands-on introduction to the analysis of financial data using the freely available R software package and case studies to illustrate actual implementations of the discussed methods. The book begins with the basics of financial data, discussing their summary statistics and related visualization methods. Subsequent chapters explore basic time series analysis and simple econometric models for business, finance, and economics as well as related topics including: Linear time series analysis, with coverage of exponential smoothing for forecasting and methods for model comparison Different approaches to calculating asset volatility and various volatility models High-frequency financial data and simple models for price changes, trading intensity, and realized volatility Quantitative methods for risk management, including value at risk and conditional value at risk Econometric and statistical methods for risk assessment based on extreme value theory and quantile regression Throughout the book, the visual nature of the topic is showcased through graphical representations in R, and two detailed case studies demonstrate the relevance of statistics in finance. A related website features additional data sets and R scripts so readers can create their own simulations and test their comprehension of the presented techniques. An Introduction to Analysis of Financial Data with R is an excellent book for introductory courses on time series and business statistics at the upper-undergraduate and graduate level. The book is also an excellent resource for researchers and practitioners in the fields of business, finance, and economics who would like to enhance their understanding of financial data and today's financial markets.
An Introduction to Analytic Functions: With Theoretical Implications
by John Sheridan Mac NerneyWhen first published in 1959, this book was the basis of a two-semester course in complex analysis for upper undergraduate and graduate students. J. S. Mac Nerney was a proponent of the Socratic, or “do-it-yourself” method of learning mathematics, in which students are encouraged to engage in mathematical problem solving, including theorems at every level which are often regarded as “too difficult” for students to prove for themselves. Accordingly, Mac Nerney provides no proofs. What he does instead is to compose and arrange the investigation in his own unique style, so that a contextual proof is always available to the persistent student who enjoys a challenge. The central idea is to empower students by allowing them to discover and rely on their own mathematical abilities. This text may be used in a variety of settings, including: the usual classroom or seminar, but with the teacher acting mainly as a moderator while the students present their discoveries, a small-group setting in which the students present their discoveries to each other, and independent study. The Editors, William E. Kaufman (who was Mac Nerney’s last PhD student) and Ryan C. Schwiebert, have composed the original typed Work into LaTeX ; they have updated the notation, terminology, and some of the prose for modern usage, but the organization of content has been strictly preserved. About this Book, some new exercises, and an index have also been added.
An Introduction to Analytical Fuzzy Plane Geometry (Studies in Fuzziness and Soft Computing #381)
by Debdas Ghosh Debjani ChakrabortyThis book offers a rigorous mathematical analysis of fuzzy geometrical ideas. It demonstrates the use of fuzzy points for interpreting an imprecise location and for representing an imprecise line by a fuzzy line. Further, it shows that a fuzzy circle can be used to represent a circle when its description is not known precisely, and that fuzzy conic sections can be used to describe imprecise conic sections. Moreover, it discusses fundamental notions on fuzzy geometry, including the concepts of fuzzy line segment and fuzzy distance, as well as key fuzzy operations, and includes several diagrams and numerical illustrations to make the topic more understandable. The book fills an important gap in the literature, providing the first comprehensive reference guide on the fuzzy mathematics of imprecise image subsets and imprecise geometrical objects. Mainly intended for researchers active in fuzzy optimization, it also includes chapters relevant for those working on fuzzy image processing and pattern recognition. Furthermore, it is a valuable resource for beginners interested in basic operations on fuzzy numbers, and can be used in university courses on fuzzy geometry, dealing with imprecise locations, imprecise lines, imprecise circles, and imprecise conic sections.
An Introduction to Ancient Egyptian Literature (Egypt Ser.)
by E. A. Wallis BudgeA superb cross-section of literature produced over 4,000 years ago, translated by the author and including extracts from The Book of the Dead, legends of the gods, historical and autobiographical literature, tales of travel and adventure, fairy tales, moral and philosophical literature, poetical compositions, and much more.
An Introduction to Animal Behaviour
by Aubrey Manning Marian Stamp DawkinsWolves excitedly greet each other as members of the pack come together; a bumble bee uses its long tongue to reach the nectar at the base of a foxglove flower; a mongoose swiftly and deftly bites its prey to death; young cheetahs rest quietly together, very close to sleep. Now in full colour, this revised and updated edition of Manning and Dawkins' classic text provides a beautifully written introduction to the fundamentals of animal behaviour. Tinbergen's four questions of causation, evolution, development and function form the fundamental framework of the text, illustrated with fascinating examples of complex behavioural mechanisms. The authors provide accounts of all levels of behaviour from the nerve cell to that of the population. The strengths of An Introduction to Animal Behaviour as a textbook include its clear explanations and concise, readable text and the enthusiasm of the authors for their subject.