Added my seventh different Diamond Matchbook of Carl Hubbell, specifically the first one on the left, which is his 1934 U1 green variation.
Weirdly, there is no master set checklist covering all of these issues, so some guest work is involved in terms of knowing just how many more Carl Hubbell matchbooks there are. I do know I need the green U3-1 and the blue U4, and I suspect/hope that makes all of them.