IIT KGP in collaboration with HRD has come up with an initiative called National Digital Library .
they have a collection of about 6.5 million e books. you can search by category,by course , by genre and download the ebooks. of-course they have app also available on google play
this is especially good for engineering students who can’t afford to buy expensive books
there are other genre books too .. you can also download audio books and in video format .
check my new video on that