Only 4 notes are required for the quest; the remaining notes are needed for the optional miniquest after completing the quest. There are 19 notes in total.
Trying to 'Copy to log' a papyrus note that has already been copied with give the message: 'You already have this information in your logbook.' However, the note will disappear from the player's inventory.
Two more chapters (18 and 19) can be found in two chests in the dungeon below the plateau. One chest is just to the east of the High Priest of Scabaras's room, while the other chest is further south, surrounded by monsters. The player may choose to take the two chapters from the chests during Dealing with Scabaras; doing so will save them from having to return later.