https://mappingthelives.org/bio/e32202ed-673d-4294-9051-12fc5a173c88?language=en
https://www.online-familieberichten.nl/pers/4549/Hans-W-Bial-1911-2000
https://archief.amsterdam/indexen/deeds/98533420-4bb6-56a3-e053-b784100ade19?person=98533420-4bb7-56a3-e053-b784100ade19
First wife: Maria Oestreicher
Second wife: Judith (Julie) Spitz