Open Access Books and Articles
Directory of Open Access Books
Directory of Open Access Journals
Edward Elgar Publishing (Includes Law, Business, and the Social Sciences. Includes complete books, individual book chapters, and journal articles)
Frontiers (all journals start with the words "Frontiers in")
OER Commons (A public digital library of open educational resources)
Open Textbook Library
Paperity (Multidisciplinary aggregator of open access journals and papers)
Public Library of Science (PLOS, a nonprofit, open access publisher dedicated to accelerating progress in science and medicine.)
Project Muse (Offers open access books, articles, and digital humanities projects from several distinguished university presses, scholarly societies, and independent not-for-profit academic publishers.)
ScienceDirect (Provides access to 356 textbooks)