In April 1942, an obituary was published in Het Joodsche Weekblad for J. Viskoop. Viskoop was active in the Jewish community in Amsterdam-North. Het Joodsche Weekblad, 24 April 1942, 4
In addition, Jokos files (numbers 25137, 55124) on this family or other family members are at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.The Jokos files reveal that a claim was lodged for compensation for valuables surrendered to the Lippmann-Rosenthal looting bank (L-claim, number 12228 / 3521).