Kogarkoite, Na3(SO4)F, from the Shalo hot spring, Main Ethiopian Rift: implications for F-enrichment of thermal groundwater related to alkaline silicic volcanic rocks - Žáček, Vladimír; Rapprich, Vladislav; Šíma, Jiří; Škoda, Radek; Laufek, František; Legesa, Firdawok (Journal of Geosciences, 2015)