https://digital.katalog.queersearch.org/s/katalog/item/63898, “Als schwuler Häftling 1934/35 in den KZs Kolumbia-Haus und Lichtenberg”, https://digital.katalog.queersearch.org/s/katalog/item/48566, QueerSearch, accessed 30. April 2025, https://digital.katalog.queersearch.org/s/katalog/item/55733