These pages are scattered around and there are only 10 of them. Once you get 25 Data Fragments, you can purchase a treasure map that shows these from any book store. This makes the achievement extremely easy. See Capped for more details on the fragments you will be collecting. Also, this achievement relates directly to the Holy Wisdom achievement. You must collect all of these to unlock the mission. You should have no problem collecting these pages.
Note: There is one page in a district you cannot get into until during/after Sequence 5 Memory 3.