He is married to Anke Beinema.
They got married on January 1, 1914, he was 21 years old.
Genealogy Data Page shows his father as George Hendriks Oosterman. However, it is less likely to be correct than the research that has already been done by presumably his family.
grandparents
parents
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Hendrik Tjeerds Oosterman | ||||||||||||||||||
1914 | ||||||||||||||||||
Anke Beinema | ||||||||||||||||||