I lost my contact for occasional look-ups in the Genealogisches Handbuch des Adels (we all get older). This is a good source for Central European nobility, particularly the many Grafen and Freiherren in the former Holy Roman Empire and successor states but not readily available in libraries and with $3,500.00 way too expensive to buy. If anybody has access to a library with these holdings (Stanford comes to mind) and would be willing to do some very occasional look-ups I would be much obliged. It's a long shot I know ...
My library might have it. They have a book called "Stammfolgen-Verzeichnisse für das Genealogische Handbuch des Adels : und das Deutsche Geschlechterbuch", and a collection of books in German that has over 100 volumes, but I'm not sure if it's the one you want or Deutsches Geschlechterbuch . I can check next week.