Infuego
Expert
I too read QBS after I saw Bob post about it back in 2010ish. Then I moved on to SPIN selling with Neal Rackham. Where QBS gave me the outline and the motivators for sales, SPIN taught me about the different KINDS of questions. And which type of question elicited the most sales; Situational, Problem, Implication, Needs.
SPIN is timeless. Start with No by Jim Camp is a very good book and gives the reader (sales person) a look into his checklist and log system for preparation and debriefing.