Swords & Spells (1976)

From the web:

Swords and spells was never officially labeled as a supplement for the D&D game, but it was nonetheless intended as the fantasy successor to Chainmail. Loved by some as a much needed update and despised by other as a hastily-produced cash grab, whatever camp you fall in, the serious D&D collector cannot ignore the presence of this book as an influence on the early D&D game.