Check out this poster known as "The Finger". It promotes shows at the Avalon Ballroom on 2/2-4/68 with art by Victor Moscoso. It has the 13th Floor Elevators fourth billed to the Fugs, Mad River & the Electric Flag. By this time Chet Helms was wary of the 'Elevators' never ending drama and tired of Tommy Hall's rap.
It turns out Helms was correct because the 'Elevators never made this gig. This might be the gig where John Ike Walton told me that he was seated in the audience. He thought it was a trip to see his band billed on the poster while he was in the audience watching the show.