This book, known as SSHE to most, is an excellent follow-on to Sklansky and Malmuth's Hold'em Poker for Advanced Players. While that book assumes you are play against thinking opponents in tighter games, this book deals specifically with how to play in the loose games one often finds online and in cardrooms which are populated with players who do not study the game.
There are excellent sections on calculating odds, betting for value and an enlightening section on playing overcards - a major leak for a lot of players. As with most Two Plus Two books, there is an extensive Question and Answer section at the end. This is another must-study book for the serious player.