Hendrika Engelsman was a daughter of Isaac Engelsman and Rebekka van der Sluis. She married 27 October 1920 in Amsterdam to Jonas Muller, a son of Hartog Muller and Riak Bierman.
City Archive of Amsterdam, archive card of Rebekka van der Sluis and website www.wiewaswie.nl .
In addition, a Jokos file (number 16891) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.