This person is commemorated on a memorial in Emmen. More information on this memorial can be found (in Dutch) on the website of the Nationaal Comité 4 en 5 mei.
The Bollegraaf family had four children: Heiman and three children who survived the war. Addition of a visitor of the website
In addition, a Jokos file (number 14240) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.