Levie van der Hak and Dora Wertheim had a son Willij.
Stadsarchief Amsterdam, archiefkaart Willij van der Hak
In addition, a Jokos file (number 55058) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.The Jokos file reveals that a claim was lodged for compensation for valuables surrendered to the Lippmann-Rosenthal looting bank (L-claim, number 2).