https://openlibrary.org/
http://www.al-islam.org/
http://publiclibrariesonline.org/
http://dsal.uchicago.edu/
http://www2.etown.edu/vl/
http://www.oalib.com/
https://www.otexts.org/
http://www.onlinecourses.com/
http://www.ahds.ac.uk/
http://arnetminer.org/
http://arxiv.org/
http://avalon.law.yale.edu/
http://www.baenebooks.com/c-1-free-library.aspx
http://books.google.com/?hl=en
http://www.gutenberg.org/
http://www.isn.ethz.ch/
