Disintegrating Thesis Notes

Disintegrating Thesis Notes are the keys to enter the lair of the resident Peerless, the Monstrous Interred Grizzle of the Bedlam dungeon. They can be rarely found as a loot from the named undead creatures inside Bedlam:

They are blessed and have a lifespan of roughly six hours. You need to collect 5 of them and exchange for the Librarian's Key via Master Cohenn's quest, called Misplaced. The reward for that quest, the Librarian's Key, is what's used to enter the Peerless Room.