https://digital.katalog.queersearch.org/s/katalog/item/63854, “Paul Emil Flechsig: Die Berechnung der menschlichen Seele”, https://digital.katalog.queersearch.org/s/katalog/item/48907, QueerSearch, accessed 29. April 2025, https://digital.katalog.queersearch.org/s/katalog/item/55570