Vintage The National Parks Centennial Portfolio Sierra Club Large Color Prints

In good shape for age. Shows signs of age and usage. All photos by Dennis Stock. Published in 1972. The collection should have 12 full size color prints, but it only has 8 for sale. Unsure which ones are missing. Each print measures about 14.75" wide and 9.75" tall. I believe the medium is a photo as the material feels slick like a photo. I do not see manufacturer or developer on the back. Each one is affixed to a larger card stock page. I do not know how they are affixed. Dennis Stock signature is under each photo and directly on the card stock. It appears the signature is printed on the card stock. Please see photos.