The company had links to a German company (I won't go into all the detail here - it's quite complicated!), and Swantje Köhler sent me an email after reading my article - she very kindly included her entry on the German company from her book Lexikon der Puppenstuben und Puppenhäuser (Encyclopaedia of Roomboxes and Dolls Houses).
This wonderful book was only published in 2004, but is out of print, and quite hard to find (Amazon says "Currently unavailable. We don't know when or if this item will be back in stock"). When I wrote to thank Swantje, and ask if she was planning a second edition, this is what she said,
I would like to make a second issue of the lexicon as I have so much more information and so many never published catalogues. But the publishers think, there is no need.
Tell all collector people to ask the Wohlfarth publishing company (Info@wohlfarth.de ) for copies (they don't have a single one) but to let them know, that there is an interest.This time I want to add an English translation too, for all my English collector friends.
So I guess we'd better get busy emailing the publisher!