Zitationen: 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. 56