Complex sentence: The notion of acoustic microscopy dates back to 1936 when S. Sokolov, USSR Patent no.49 (31 Aug.1936), British Patent no.477,139,1937, and, 1939.
Split into simpler sentences: The notion of acoustic microscopy dates back to 1936 when S. Ya. Sokolov S. Sokolov, USSR Patent no.49 (31 Aug.1936), British Patent no.477,139,1937, and, 1939.