OBEN: Photo Timo Bechtoldt, D. GRUEN & SONS Glashütte i. Sa. GmbH: SAECHSISCHESCHWEIZ - OSTERZGEBIRGE, Basteibrücke
LINKS:
http://vintagegruen.org/vgforum/index.php?t=finduser&btn_submit=Find&
http://immigrantentrepreneurship.org/entry.php?rec=219
http://www.gruenwristwatches.com/new-dating-method-2.php
http://vintagewatchforums.com/viewforum.php?f=33
http://www.thewatchguy.com/pages/GRUEN.html
http://gruen.watch/?page_id=209