https://www.joodsmonument.nl/nl/page/321957/isidor-alexander-fontijn
https://collecties.kampwesterbork.nl/persoon/https%3A%2F%2Fkampwesterbork.nl%2Fdata%2Fperson%2F16618682
Story: EHRI - Fontijn, I.A. (ehri-project.eu)
https://archief.amsterdam/indexen/deeds/98533418-1a22-56a3-e053-b784100ade19?person=98533418-1a23-56a3-e053-b784100ade19
Isidor Alexander Fontijn (1900 - 1975) - Genealogy (geni.com)
https://www.recherche.bar.admin.ch/recherche/#/fr/archive/unite/5196916?q=isidor%20fontijn