1. Beckwith, T. P., andC. E. Weaver, Sonic energy as a lethal agent for yeast and bacteria. J. Bacter. (Am.)32 (1936), 361–373.
2. Bergmann, L., Ultrasonics. 1938, Oxford.
3. Boas, F., Die Pflanze als kolloides System. 1928, Munich.
4. Boyle, R. W., andJ. F. Lehmann, The relation between the thickness of a partition in a medium and its reflection of sound waves by the ultrasonic method. Physiol. Rev. (Am.)27 (1926), 518.
5. Bruel, P. V., andU. Ingård, A new high speed level recorder. J. Acoust. Soc. (Am.) (21),2 (1949), 91–93.