AD&D Sourcebook published in 1980, written by James M Ward with Robert J. Kuntz.
A reference cyclopedia of gods and heroes from mythology, legend, and fiction for the AD&D game. The Nehwonian mythos is included. Included is a brief description of the Nehwon mythos and of some the chief organizations within. After that are entries for Fafhrd and the Gray Mouser, some other major characters, various monsters, and the pantheon of gods. The entries include stats for the game and a description. Most of the interior illustrations were created by Paul Jaquays (now Jennell Jaquays), and have a style fitting for the Nehwon stories.
Only the Nehwon material is listed here: