Isaac de Leeuw was a son of Gerard Isaac de Leeuw and Leentje van de Kar.
City Archive of Amsterdam, archive card of Meijer Visser.
According to a list with shops of Jewish owners, compiled by the Amsterdam police in 1940, this family had a tobacco shop, address: Koningsstraat 38 in Amsterdam.
Abstracts of the police archives which are currently at the Amsterdam municipal archives