AMA:  https://www.americanmotorcyclist.com/

D6: http://www.d6mx.org/

D6 Trials:  http://d6trials.com/

Mid-Atlantic Vintage Trials (MAVT):  http://www.mid-atlantictrials.com/

AHRMA Vintage Racing:  http://www.ahrma.org/ 

https://www.facebook.com/vintagevintageharescramble/