Propagators of Estonian crater theme in the English-language world. A. Ivan Reinwald (on the right) and Clyde Fisher, active educator and traveler from the American Museum of Natural History (https://en.wikipedia.org/wiki/George_Clyde_Fisher), on the floor of the Kaali crater no. 2 in 1936 (from Reinwald, 1938b). B. Leonard James Spencer (1870–1959), a renowned British mineralogist, Keeper of Minerals in the British Museum Natural History, and Reinwald’s collaborator (from Tilley, 1961).