I have a Kodak Colour Dataguide from 1968 and another from 1974 which both came with a negative [Ektacolor Professional S - C22 Process] and an accompanying 2x3 inch print. They were definitely part and parcel of the original publication as the envelope's edge is incorporated into the spiral binding.
I have a Q-60 Kodak Color Reproduction Guide from 1977. The E-4, E-6, K-25 and K-64 color images look pretty good. Not so for the E-3 images.