This is not a guide, more of hints.
Since I've been using the Walkthrough.
-You need 31 documents and 31 notes.
-There is a list on:http://www.powerpyx.com/guide/outlast-all-document-and-note-...
-Create several savegames in case you missed one.(have to replay the whole lot though)
Be aware of chapter 8 beginning, there are 2 items at the start.