Jacob Walvis was a son of Kalman Walvis and Grietje Speijer. He married in Amsterdam on 27 July 1938 to Selma Stuiver.
City Archive of Amsterdam, archive card of Jacob Walvis.
In addition, a Jokos file (number 30090) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.