In December 1943, two members of the Kolonne Henneicke found Charles Salomon Viskoop at the address he was being hidden. He was ten months old at the time.
A. van Liempt, Kopgeld. Nederlandse premiejagers op zoek naar joden, 1943 (Amsterdam 2002) 239-240
In addition, a Jokos file (number 56029) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.