What site can I use to download books onto my iPhone for free?

I have the app 'iBooks' where I used to store all my books but my phone got wiped and now the site I used to use have taken down the books I'm looking for (Harry potter) the site I used to use is www.epubbud.com and now I can't find a website that is even a little like this.

Hi,
Great, you can download many no.of ebooks for free, and it is the most used app by book lovers,
Go for bookchums app.

https://play.google.com/store/apps/details?id=com.engage.bookchums2&feature=search_result#?t=W251bGwsMSwyLDEsImNvbS5lbmdhZ2UuYm9va2NodW1zMiJd

http://www.bookchums.com/

http://www.bookchums.com/ebooks.php