Bertha de Vries was a daughter of Mozes de Vries and Rozetta Engers. She married in Rotterdam on 30 June 1909 to Pinehas de Rooij (de Rooy), son of Mozes de Rooij and Sara Boeken.
Municipal archive of Rotterdam, register of marriages .
In addition, a Jokos file (number 14596) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.