Marcus Ketellapper was the son of Isaäc Ketellapper and Leentje Frinkel. He married 26 January 1933 in Amsterdam to Grietje Cohen, a daughter of Jacob Cohen and Rosa de Magtige.
Marcus was the brother of Rachel, Jetje and Simon Ketellapper.
City Archive of Amsterdam, archive cards of Isaac, Marcus a…
In addition, a Jokos file (number 50619) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.