Masterpieces of Handicap Go
Logan? - I think this is a phenomenal series. The value of playing through handicap games cannot be underestimated; they present a clear picture of the differences between a weaker & stronger player. Almost all of the games are memorable and will leave an impression on your mind. At 7$ apiece (2012) it's a steal!
Anonymous - Both books are very good. Nice annotations, some historical context, lots of good moves (and bad moves). People always want to study even games, but handicap games can be very instructive!