One of them will tell you that Goblins with big eyes have broken through a on the west side of the library until you find a Goblin Symbol Book.
Goblin symbol book, Examine: A book about the ancient goblin tribes. Weight: 1.00 kg. Members: Yes, Quest item: Yes, Tradeable: No.
Runescape item database containing all Runescape items including plenty of information on what to do Item Database» Goblin symbol book.