Notes
Bob Schwartz, who attended the show the next night, reports "I was in SF at this time and I am pretty sure this show didn’t happen." He was from Florida, knew Vassar, and so has a lot of credibility. Correspondingly, we now list this show as uncertain. At the same time, on the 7/21/73 rehearsal, Vassar mentions doing a tune in G "last night". So maybe they practiced instead of playing live?
listing: San Francisco Chronicle, July 20, 1973, p. 50.
Keystone calendar bills "Bluegrass", then band name, band members and instruments, including "guest fiddler" Vassar Clements. BB pretty much the same, but says "special guest fiddler from Nashville". HDR listing day of first show bills merely "surprise".
ref: July 1973 Keystone Berkeley calendar image, via Merl Jr., who got it from Fred;
preview: “Jerry Garcia’s Bluegrass Group to Play at Keystone,” Oakland Times, July 17, 1973, p. unk;
ad: Berkeley Barb, July 19-August 1, 1973, p. 21;
listing: Hayward Daily Review, July 20, 1973, p. 44;