Wolf (Willy) van Beetz (1912 - 1942) - Genealogy (geni.com)
https://archief.amsterdam/indexen/deeds/98533400-a1a1-56a3-e053-b784100ade19?person=98533400-a1a2-56a3-e053-b784100ade19
https://www.maxvandam.info/humo-gen/family/1/F50970?main_person=I13302