https://digital.katalog.queersearch.org/s/katalog/item/41131 and https://digital.katalog.queersearch.org/s/katalog/item/45291, “Lexikon der Sexualaufklärung”, https://digital.katalog.queersearch.org/s/katalog/item/47685, QueerSearch, accessed 16. Juni 2025, https://digital.katalog.queersearch.org/s/katalog/item/30083