1. H. Helmholtz, Crelle, 57, 1859; Theory of Oscillations in Tubes with Open Ends (1860).
2. H. Helmholtz, Vorlesungen über die Mathematischen Prinzipien der Akustik (Leipzig, 1898).
3. O. Reynolds to Lord Rayleigh (J. W. Strutt), unpublished letter on the reciprocity of sound (Fallowfield, Manchester, October 2, 1875).
4. J. Tyndall, in Sound, a Course of Eight Lectures (Longmans, Green, and Co., London, 1867), Lecture 6, pp. 217–254.
5. L. Rayleigh (J. W. Strutt), R. Soc. London 25, 118 (1876); in Acoustics: Historical and Philosophical Developments, Ed. by R. B. Lindsay (Dowden, Hutchinson and Ross, Stroudsburg, Pa.), Paper 36, pp. 402–406.