There isn't much on Pivotal Response Training. The research never really came through in a big way. Maybe it still will, but I haven't seen any.
PRT is exactly what we all wish ABA could be. You have lots of fun teaching a few key cusp skills and then Viola! these skills automatically generalise and new skills are easily built on these cusp skills.
The fact of the matter is that many kids with autism have a hell of a time generalising skills to new people, places, and stimuli. There may not be a better way to cope with this than to doggedly teach skills in a wide variety of stimulus conditions.
PRT has some good ideas, and good behaviour analysts should know about PRT and incorporate some of these ideas when it is appropriate. The research does not yet support the claims that a PRT model is better than the alternatives.
Verbal Behaviour, ESDM, PRT, Lovaas-style discrete trial teaching are all variants on a theme. Different kids will need different kids of reinforcement and be motivated by different things. The basics of learning theory apply to all these interventions. And they all work. They work best when done early and intensively.