Joseph de Magtige was a son of Elkan de Magtige and Hadasse Sanders. He married in Amsterdam on 23 October 1935 to Dora van Gelderen, a daughter of Manuel van Gelderen and Duifje Polak.
City Archive of Amsterdam, archive card of Joseph de Magtige .
In addition, a Jokos file (number 51615) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.