I'm not to sure if you call this a mini poster, playbill, but it's a small cardboard poster
about 4.25x7.25 inches. I got this in an auction run by Glen's sister Janice Buxton.
At bottom in small print in red rule margin it reads
Last minute cancelation - John Lee Hooker.
From SickThingsUK they list "eyewitness suggest Alice Cooper was too drunk to perform."
August 3, 1969, Michigan Sportsman's Park