I don't know if you'll find any "scholarly" sources that you could use, but other than asking people on here you should check out www.bmxtrix.com. Paul has some write ups about the history of the sport back into the eighties up until maybe 2000. Ask people on here too. The older guys LOVE to talk about that stuff
http://www.23mag.com/
www.vintagebmx.com ...Man I hated those research papers more than anything I used to try to do them on bmx topics too it was always a pain in the ass to get all the citations,and good story etc, flatland kicks ass, but I would do it on bmx as a whole or maybe just a more general topic, thats just my advice
this is what im writing my jrp on so if you guys know any cites or somewhere i can find all the imformation from the video "joe kid ad a stingray" or something like that.