Karl Koppel Weisz Bakery, Vienna Phone Book Listing (A 32, 210). See notes 1.

http://www.digital.wienbibliothek.at/wbrobv/periodical/zoom/269523

The address of the bakery was:
Franz Hochedlinger-Gasse 24.
Leopldstadt, Vienna, Austria
(Leopldstadt is a district of Vienna that had a high percentage of Jewish people.)
Their home was just around the corner at Floßgasse.

German: Adolph Lehmann's Allgemeiner Wohnungs-Anzeiger
English: Adolph Lehmann's General Housing Indicators

German: [Firmenverzeichnis] 2. Protokollierte Firmen.
English: [Business Directory] 2. Documented Company.

German: Nach den Veröffentlichungen des Ha Wien
English: According to the publications of Vienna