A review by klagge
The Elusive Shift: How Role-Playing Games Forged Their Identity by Jon Peterson

Interesting discussion of the tension between the cultures of wargaming/simulation and fantasy storytelling in the early years of D&D and roleplaying as a hobby, drawing mostly on zines. If you are going to read one book on the genesis of RPGs, though, I think "Playing at the World" is more interesting (but good luck finding a copy).