https://www.mappingthelives.org/bio/92580e7c-037c-4e4b-bce5-989dca696c1d
Siegfried Arthur Marx (1894 - 1983) - Genealogy (geni.com)
https://www.maxvandam.info/humo-gen/family/1/F60037?main_person=I159126
https://archief.amsterdam/indexen/deeds/985333f4-d4d0-56a3-e053-b784100ade19?person=985333f4-d4d1-56a3-e053-b784100ade19