The Backgammon Book

Oswald Jacoby and John R. Crawford are the inventors of the 2 most famous optional rules of modern backgammon :

• Jacoby rule: only in money game, Gammons and backgammons count only as a single game if neither player has offered a double during the course of the game,

• Crawford rule: only in match play, when the leading player comes within one point of winning the match, the following game is played without a doubling cube.

The Backgammon Book is the first to mention these 2 rules and Beaver (but does not mention Raccoon).