https://www.dutchjewry.org/genealogy/vriesman/249.shtml
Rudolph de Metz (1885 - 1960) - Genealogy (geni.com)
https://www.maxvandam.info/humo-gen/family/1/F67943?main_person=I86559
First spouse: Christina Ekstein https://www.joodsmonument.nl/en/page/123174/christina-ekstein