Alfred de Jonge was the son of Heiman Israel Simon de Jonge. he was married to Henny Rozenboom. They were both born in Germany, just across the border of Nieuweschans.
Addition of a visitor of the website
In addition, a Jokos file (number 8966) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.