Need some assistance from Colorado/Aspen Photographers

I am writing an article for publication and I need to locate a photographer, or possibly his heirs, to obtain permission to use a photograph in an article. The photographer is Bob Bishop, who lives in Aspen, Colorado. He was a participant in the 1951 Aspen Photographer's conference. The photo is an image of the participants in that event.

If anyone knows Bob, please let me know how I can contact him.

Thanks for your help.

Sorry, I can't help you find Bob. I met and was somewhat aquainted with him back in the 60's. He hung out in Denver a lot back then. Used 35 mm about as good as any one I ever saw! I will email a friend that also knew him and see if he has any ideas on how to locate him.

Charlie.........................