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The story mentions that Seth Barnes Nicholson discovered Lysithea and Carme in 1938. He also discovered Sinope in 1914 and Ananke in 1951. Presumably the others included those found by Galileo Galilei in 1610 (Callisto, Europa, Ganymede and Io), Amalthea (1892), Himalia (1904), Elara (1905) and Pasiphae (1908).