https://digital.katalog.queersearch.org/s/katalog/item/40607 and https://digital.katalog.queersearch.org/s/katalog/item/40615, “Die Homosexualität: Eine Streitschrift”, https://digital.katalog.queersearch.org/s/katalog/item/48541, QueerSearch, accessed 1. Mai 2025, https://digital.katalog.queersearch.org/s/katalog/item/16777