Original 1st printing 14&1/8 x 19&7/8" concert poster for Texas psychedelic fuzz-rock legends the 13th Floor Elevators (featuring Roky Erickson) and the Sir Douglas Quintet (featuring Doug Sahm and Augie Meyers) at the Avalon Ballroom in San Francisco, CA on 9/2-3/1966. Art by (and SIGNED in pencil by) Stanley Mouse and Alton Kelley, image ("Tree House") is # 24 in the Family Dog/Avalon series. Medium-thick flat vellum stock poster is in very good to excellent (B/B+ to B+) condition; a series of nine (9) pin/tack holes in each of the corners and scattered at various points around the outer edges of the image/margins (several of them are quite well camouflaged), a tiny nip out of the left center margin, a couple of tiny pinch/stress dings and a whisper of toning, otherwise fine. Overall a very sharp-looking SIGNED example of this classic '66 1st printing FD poster.