Bob, there's a parallel thread about Eliot Porter dye transfer prints for sale by some outfit that leaves a lot of things unanswered. He did print some of his own images, but not in volume or at a late date. I am aware of who did commercial printing for him - both an assistant and a specific big lab. But that is the kind of disclosure I would expect from a reputable broker, as well as the actual date of printing and whether or not any of these have been on display somewhere, because dye transfers are only relatively permanent and quite affected by UV etc. Since only some like the like the bird prints are specifically attributed to him, I guess a potential customer would have to ask in the other cases, and hopefully they have
a correct answer.