I'm absolutely not going to post my source, as 1) he/she is a professor at my university, which would compromise my anonymity, and 2) I don't think that he/she would appreciate me posting his/her personal opinion on a public website. I do not believe this person has published specifically about play therapy, but it is his/her general area of expertise (that is, tx for childhood disorders in general). I did make it quite clear in my initial post that I don't have any sources to back this up, only that I heard it from a prominent individual. I don't think it would be a very good policy to insist that everyone has sources at hand before posting opinions-- this is a public forum, not a peer reviewed journal!