Leo Weiser, recte Leiser Weisser, from Galicia, opened a mail order business with bookstore at Kaiserstraße 89 in Vienna's 7th district in January 1924, with a further outlet at Tuchlauben 5 in the 1st district from September 1929. It focused on export business, specializing in scientific and art history books and lexicons. The business expanded in 1931 with the opening of Antiquariatsbuchhandlung Weiser & Cie. in Ljubljana, Yugoslavia (now Slovenia). In 1938, Weiser lived with his wife Eva, née Klein, at Nelkengasse 2 in the 6th district. As both were of Jewish origins, they were persecuted by the Nazis and fled together on 23 March 1938 after the annexation via Czechoslovakia to London, from where they emigrated to the New York in August of that year. In July 1938, the Vermögensverkehrsstelle (VVSt) (Property Transaction Office) appointed Richard Riedmann as temporary administrator of the company in Vienna and in September 1939 as trustee and temporary administrator of Leo Weiser's two companies. Alfred Wolf, who had applied to the VVSt to Aryanize the business at Tuchlauben 1, came to an agreement in November 1938 with the Devisenstelle (Foreign Exchange Office), to take over only the books and inventory that could be sold. After the VVSt assigned the mail order business to him on 22 December 1938, he and Riedmann moved the stocks and inventory in February 1939 from Weiser's business to a new antiques business at Schottenring 35 in the 1st district without concluding a sales agreement. Weiser's mail order business was liquidated in March 1940. In January 1941, the Vienna Gestapo seized and expropriated Weiser's remaining assets, including two properties in Berlin and the contents of his apartment at Nelkengasse 2 in Vienna's 6th district. Leo Weiser and his wife Eva were both stripped of their citizenship.
After the US military government had placed Antiquariat Alfred Wolf in August 1946 under public administration and several public administrators of Weiser's shares had been appointed and removed, Weiser was appointed public administrator of his 50 per cent share in 1953. In December 1956 the Restitution Commission of the Landesgericht für Zivilrechtsachen (provincial court for civil law matters) approved Weiser's restitution claims and awarded the entire company to him. In September 1957 the sister of Riedmann, who had died in the meantime, purchased Antiquariat Alfred Wolf from Leo Weiser, who died in New York in 1974. The systematic provenance research at the Universitätsbibliothek der Medizinischen Universität Wien (University Library of the Medical University of Vienna) identified twenty-four books that had been purchased between March 1941 and August 1945 by the Institut für Geschichte der Medizin (Institute of the History of Medicine) from Antiquariat Wolf and had been listed in Riedmann's July 1938 inventory of Antiquariat Leo Weiser at Tuchlauben 5. Leo Weiser's heirs are currently being sought for the purpose of restitution.