https://digital.katalog.queersearch.org/s/katalog/item/51776, “Der Kreis - Le Cercle - The Circle und sein Nachlass”, https://digital.katalog.queersearch.org/s/katalog/item/42696, QueerSearch, accessed 17. Juni 2025, https://digital.katalog.queersearch.org/s/katalog/item/55222