As an extension of Sepharblue's solution, i found the title of the books DO NOT have to be different, as an example, i read books everywhere i went using Sepharblue's guide, just reading the book while it was still on the bookshelf, but i mustve read at least 12 copies of The Adventure 1, and this seemed to count towards my 50 count.
I didnt try and just open a bookshelf and read the same book 50 times, but i did read the same named books on different bookshelves!
Hope this helps guys, just go and read every book you see, dont worry about the titles.