The official Advanced Dungeons & Dragons Monster Manual by Gary Gygax. 4th Edition, August 1979 stated on title page.
The corners of the cover have some very minor damage, and other than a few dings and dents the book is in very good condition, especially the pages and the artwork.
An alphabetical compendium of all of the monsters found in the Advanced Dungeons & Dragons game, including attacks, damage, special abilities, and descriptions.