Play Gin To Win, by Charley Killebrew, Manny Chan, Pete Billac
Teaches how to play percentages, count cards, use the upcard, speculating, knocking, reading opponents' body language, cheating and courtesy. With illustrations and interesting anecdotes.

How to Win at Gin Rummy: Playing for Fun & Profit, by John Patrick, Pramod Shankar, Lyle Stuart
Learn the scientific basis for Gin Rummy. Easy to read, requires no mathematical background on your part and is virtually guaranteed to improve your understanding of the game and increase winnings.

Gin Rummy: How to Play and How to Win, by George Gin Rummy
A book about Gin Rummy.