https://digital.katalog.queersearch.org/s/katalog/item/44235, “The Homosexual Emancipation Movement in Germany: Lesbians and Gay Men in Society, History and Literature”, https://digital.katalog.queersearch.org/s/katalog/item/50293, QueerSearch, accessed 14. März 2025, https://digital.katalog.queersearch.org/s/katalog/item/27704