Here are 20 online sources for free e-books that you can use on classroom devices, for personal devices or recommend to your students.
http://www.lifehack.org/articles/lifestyle/20-online-resources-for-free-books.html?utm_source=post&utm_medium=manypeopleareturningfromtraditionalpaperbasedbookstoereadersthesedaysandthoughthedemandforprintedbooksmightbelesseningsomewhatfolksarecertainlynotreadinganyless&utm_campaign=innerlink_
http://www.lifehack.org/articles/lifestyle/20-online-resources-for-free-books.html?utm_source=post&utm_medium=manypeopleareturningfromtraditionalpaperbasedbookstoereadersthesedaysandthoughthedemandforprintedbooksmightbelesseningsomewhatfolksarecertainlynotreadinganyless&utm_campaign=innerlink_