Whatever you read back then or will read or whatever Robert told you back then was exactly what Robert knew since, Robert devoted most of his time awake in sharing whatever he knew with others.

A portion of Robert's collection was sold by Potter & Potter Auctions and, as far as I can remember, Robert explained a lot about those chips right here and, whatever all he wrote is archived if you want to try searching the archive index by clicking the link above.

You might want to check out that auction site as well in case there was some mention there as well.

Best of luck...