1. Interviews
2. Personal interview with Artha van der Werf, daughter of Anne Gerrit van der Horst (fiancé of Pos 1930s) and Willy Egbers, daughter of Artha van der Werf, 26 August 2015, Houten, the Netherlands.
3. Personal interview with Hans Krol, volunteering curator, Noord-Hollands Archief, 22 September 2016, Haarlem, the Netherlands.
4. Personal interview with Iep van Dongen (niece of Mary Pos), 15 November 2019, Wormerveer, the Netherlands.
5. Personal interview with Ru Pos (nephew of Mary Pos), 5 September 2017, Zaandam, the Netherlands.