Isaac Kool married 20 July 1942 in Amsterdam to Isabella Polak, a daughter of Saul Polak and Sara Ancona. City Archive of Amsterdam, archive card of Isabella Polak and Joseph Kool.
In addition, a Jokos file (number 50765) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.