I don't think it's Wabash.. Alcazar would be closer.. There are really a lot that are similar. Folkwang, Frieda Mohr...
2 sites I would recommend:
http://www.historiciris.org/
http://www.irisparadise.com/
The nice thing about Iris Paradise is that they have sections by breeder. You might check with the European breeders they have listed.
You can search by decade on the historic Iris site. It's a little tedious, but you should come up with some good guesses to start to narrow it down. I'm guessing pre-1930, and probably earlier..
