Yes, here is a link to the William Matthews gallery which is in downtown Denver across the street from the Rockmount Ranch Wear store where the shirts were ordered.
http://www.williammatthewsgallery.com/William Matthews is a neighbor of mine and his daughter went to school with my daughter.
I see he is selling a copy of the book signed by him for $150.00. Friend Rodney gave me a copy signed by Annie Proulx and one of these days I'll get him to sign it too.