https://digital.katalog.queersearch.org/s/katalog/item/41545, “Queer Identities and Politics in Germany: A History 1880-1945”, https://digital.katalog.queersearch.org/s/katalog/item/48415, QueerSearch, accessed 30. April 2025, https://digital.katalog.queersearch.org/s/katalog/item/18400