Identified as Ditmar Urbach. (Thanks to members ginni and csmarshall.)
Ginni writes, "Ditmar-Urbach, Znojmo, in Moravia of the Czech Republic (formerly Znaim, Moravia, Austria) did have a ink stamp of a swan on three lines of water from 1920 to 1945, but I do not find a foil label for them." According to Marshall, this sticker "was used after 1930 but still in the period of Richard Lichtenstern (ended 1945). The swan mark was introduced by Ditmar-Urbach and later adapted and continued by both the (then Czech) Teplitz and Wilhelmsburg facilities."
Identified as Übelacker Zierkeramik. (Thanks to csmarshall.)
Marshall notes that this sticker was used around 1962 by Übelacker Zierkeramik (a.k.a. Ü-Keramik) from Ransbach-Baumbach (Rhineland-Palatinate). The company operated under that name from 1955 until 1990. For more information on this company, click here.