Original 1st printing (Maron Lithograph credit) 15&1/4 x 23&1/4" concert poster for Quicksilver Messenger Service appearing with Van Morrison, Clear Light and Blue Cheer at the Earl Warren Showgrounds in Santa Barbara, CA on 9/30/1967.

 Artist unknown/not credited, medium flat vellum stock poster is in near mint to excellent (A-/B+ to B+) condition; aside from a few nearly-invisible  handling creases hiding within the image area and a couple of tiny edge nips, it is a VERY clean example of this brightly-colored image from the Jim Salzer series; check out a great informative list of 1960's-era shows (including this one) held at the Earl Warren Showgrounds:

http://earlwarrenshowgroundsetal.blogspot.com/2010/09/earl-warren-showgrounds.html