Isidor Heinrich Grünberg was a son of Bernard Grünberg and Ernestine Meisner. He married Hilde Zwettels in Berlin during the 1920s. He and his wife had a daughter, Stefanie, who was known as Steffi.
The following documents remain from them:
an excerpt from the Lvov (the current name of Lemberg) register of births for Isidor Heinrich Grünberg
a certificate of his circumcision by the mohel R.F. Bodek, with Rabbi Alexander S. Halpern as the sandak
an employment agreement signed in Berlin on 27 September 1927
an excerpt from the City of Amsterdam's register of births, deaths and marriages indicating that Isidor Heinrich Grünberg from Berlin had settled in Amsterdam on 31 October 1933
a statement from the German consulate general in Amsterdam dated 14 December 1935, indicating that under German law he had lost his German citizenship and had surrendered his German passport
a statement from the mayor of Amsterdam, dated 21 March 1939, indicating that he was the director of a business and lived at 103 Olympiaplein
a statement from the U.S. consulate in Rotterdam, dated 27 March 1939, indicating that he had requested permission to immigrate to the United States
a handwritten letter to relatives in the United States dated 8 December 1940, drafted on the stationery of the U.S. consulate in Rotterdam
the deed establishing the partnership H. Grünberg & Co.
an excerpt from the Registry of Companies at the Chamber of Commerce and Factories in Amsterdam, indicating that Isidor Heinrich Grünberg, Jacob Semmel and a third person ran a partnership named H. Grünberg & Co., registered at 137 Keizersgracht in Amsterdam, dedicated to manufacturing and selling women's overcoats and all possible related items, and that control of this company had been assigned to a trustee following orders from the state commissioner
a letter dated 14 January 1942 confirming that Isidor Heinrich Grünberg was hired as a cutter at the fashion warehouse Krause en Vogelzang
a bill of sale in which Isidor Heinrich Grünberg and his wife Hilde Zwettels sold the contents of their home at 103 Olympiaplein in Amsterdam to a third party
a sheet of passport photographs of Isidor Heinrich Grünberg, his wife Hilde Zwettels and their daughter Stefanie
an 'alien's passport' issued on 20 May 1938 to Hilde Grünberg-Zwettels and her daughter Stefanie.
Addition