Following last week's post, this week I will do another AD&D book.
I present Greyhawk Adventures.
This allows you to set games on Oerth. It provides information about deities, heroes, monsters, magical items, spells, and more.
Originally started as a simple dungeon under a castle, Greyhawk has expanded to a more complex dungeon, the city of Greyhawk, and an entire world. It has been used as the setting for many published adventures.
-Dean