found: Historische Güterwagen, c1985:t.p. (Waggonfabrik Uerdingen A.G.) p. 31 (est. in 1898; in 1959 absorbed the Düsseldorfer Waggonfabrik Aktiengesellschaft, Düsseldorf [no publs. in LC data base]; name changed to DUEWAG Aktiengesellschaft in 1981)
found: Düwag, 1968:cover (Waggonfabrik Uerdingen AG used the trade name and logo "Düwag" inherited from the Düsseldorfer Waggonfabrik AG)
found: Duewag Ag i A, website, viewed via www, Aug. 15, 2007:(Düsseldorfer Waggonfabrik AG merged into Waggonfabrik Uerdingen AG in 1935, not 1959)