here we bring some list of useful website which can be useful for you. & if you find it useful consider to like our fb page.
https://openlibrary.org/
http://www.openculture.com/free_ebooks
http://etc.usf.edu/lit2go/books/index/
http://www.librophile.com/#!/ebooks/popular/free
http://manybooks.net/titles.php
http://www.feedbooks.com/publicdomain
http://www.gutenberg.org/ebooks/
http://research.allacademic.com/
http://www.oxfordjournals.org
https://openstax.org/
http://www.wdl.org
http://www3.interscience.wiley.com/
http://www.vakilno1.com/for Indian laws and supreme court judgments
http://www.feedbooks.com/
http://www.e-booksdirectory.com/
http://www.freebookcentre.net/ for college studies
https://www.free-ebooks.net
http://www.islamicbulletin.org/services/all_ebooks_p1.aspx Islamic
http://www.buddhanet.net/ebooks.htm buddisum
www.obooko.com/
http://comicbookplus.com/ comics
http://www.ccel.org/ for christian books
http://psychclassics.yorku.ca/author.htm psychology materials
http://digilibraries.com/
PDFbooks
Wikibooks
http://www.thefreelibrary.com/
www.emeraldinsight.com
http://books.google.com/books( Downloader essential)
ebook.com (only Limited Preview, DNL Reader installation must
Online Books
FreeBookSpot
GetFreeEBooks
FreeTechBooks
BluePortal
OnlineComputerBooks
BookYards
The Online Books Page
EBookLobby
Dwalin
Witguides
e-Library
BookBoon
PlanetPDF
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