The Hamburg Art & Crafts School: "Kunstgewerbeschule".
The Artschool were Ilse Koch studied and her husband Hugo Amberg teached drawing in 1922-1923 (and after ....?)
Carl Otto Czeschka (* 22.October 1878, Vienna † 20. July 1960 Hamburg)
designed these school windows
The Museum for Arts and Crafts build in 1875, located opposite the Central Station (Hauptbahnhof, destroyed and rebuild after WW2) in Hamburg probably will have works by this Hamburg couple in deposit or on display.
Hamburg Central Station ca. 1920