Spreadsheet of textbooks sorted by course abbreviation and number.
OpenStax CNX (Rice University)
Open Course Library
College Open Textbooks
eBook Central Science & eLibro - Anatomy & Physiology
eBook Central Science & eLibro - Biology
EBSCO eBooks
OpenStax CNX
Open Learning Initiative (Carnegie Mellon)
Community College Consortium
MERLOT (California State University)