As far as I know, Magriel's Safe vs Bold criteria is probably most cited part of all backgammon literature.
In all the books I've read it is at least mentioned, and in many it is explained in the detail.
Magriel wrote this rule 35 years ago, much before the backgammon bots era, but it has passed the test of time and it is still very valuable rule when deciding about candidate moves in the middle game.
