In late 2013 the German Gun Collectors Association www.germanguns.com published a 30 page journal, “Der Waffenschmied No. 45”, on the Teschner & Co, Wilhelm Collath, Frankfurt a.d. Oder, company. It is available from their bookstore, plus a reprint of a catalog.

Contents:
The Company Teschner & Co.(on company history),
The “Collath” action and Collath inventions (on the history of the Renette – Gastinne – Lancaster – Berger – Collath slide and tilt action and 12 other gun patents + 27 registered designs assigned to the Collaths)
Collath Picture Gallery
Ammunition by Teschner & Co., W.Collath, tm TESCO
Lots of pictures.