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Anonym 1944: [Muttkowski, R. A.] Annals of the Entomological Society of America, Columbus/Ohio 37, S. 135, B15 10270
Seehausen, M.; Turiault, M.; Fliedner, H.; Deliry, C. 2023: "A nice old greybeard" - Friedrich Ris' correspondence archived at the Senckenberg Museum Franfurt/Main, Germany. Report/ International Dragonfly Fund. A Journal of the International Dragonfly Fund., Frankfurt 2023 (180), S. 1-84, 12 326, pp. 36-38