Does anyone of you have access to the fixed price lists No. 57 (Spring 1992) or No. 58 (Fall 1992) of that dealer? I have a Gallienus Sestertius (VIRTUS AVGG) that came with a collector´s ticket stating that it was bought there (for 370 Swiss Francs) in 1992 and would be glad if someone could confirm this or add any other info. Some of the coins (mostly Greek) seem to have come from the collection of a "Dr. G. W.".
For anyone who stressed he's around for it, note also it may be filed under Credit Suisse or Schweizerische Kreditanstalt in some libraries.