Books are available all over the world so as long as you're actively seeking to work on this trophy, netting it by the time you hit one of the major cities of Rathir or Adessa shouldn't be too difficult.
A helpful hint if you aren't looking to steal every book you come across in inns and people's houses is simply read the book (without stealing) by hitting Square twice. This will read the book and it will count towards your goal and you will not steal the book or have to worry about not getting caught.
Again, books can be found all over the world within towns and occasionally in Dungeons. Additionally Adessa and Rathir both have large libraries with lots of books to both read and purchase. Scrolls and the like DO NOT count toward this trophy, however reading two different copies of the same book DOES count.