This is cool!
This is an historic Art on the Rocks advertisement that appeared in Time magazine, July 22, 1966, Vol. 88, No.4. There were four different art fairs that were chosen from different regions of the country sponsored by The Northern Natural Gas Company.
You can see the full ad by clicking the image or going to https://time.com/vault/issue/1966-07-22/page/48/
Does anyone out there have a copy of this issue saved? We would be interested in having it for our archives. Please email Diane Kordich at dkordich@nmu.edu