Wolf Zwaap and Sara Olivier lived also on the Nieuwe Prinsengracht 50-huis. There they were the neighbours of Wolfs brother Michel Zwaap and his wife.
Addition of a visitor of the website
In addition, a Jokos file (number 52440) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.