Which textbooks are in the NIMAC?
The effective date for the NIMAC was July 16, 2006. After that date, publishers are required to submit files to the NIMAC for books adopted by the public K-12 education system when the request is made in writing at the point of print book purchase. If you believe that files should have been submitted to the NIMAC but you aren't finding them there, you may want to verify with your school's purchasing department whether the purchasing contract included a requirement for NIMAS files.
If your purchasing department did not include language about placing files in the NIMAC, you should check the NIMAC anyway. The NIMAC is also happy to help you follow up with publishers regarding required files that are not yet in the system. NIMAC books are added to Bookshare at the request of educators at K-12 organizations.