Clara Viskoper was a daughter of Elias Viskoper and Eva Boas. She married on 6 April 1938 to Israel Cohen, son of Isaac Cohen and Bertha Kruijer.
Civil Registry of Den Haag, family registration cards of Elias Viskoper and Isaac Cohen .
In addition, a Jokos file (number 8343) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.