1. J.W. Strutt (Baron Rayleigh): Proc. London Math. Soc., 17, 4 (1885); see also: The Theory of Sound (MacMillan, London 1896; unabridged 2nd revised edition: Dover Publ., New York 1945)
2. G.W. Farnell, in Physical Acoustics, vol. 6, ed. by W.P. Mason, R.N. Thurston (Academic Press, New York, 1970), p. 109
3. A.A. Maradudin, in Nonequilibrium Phonon Dynamics, ed. by W.E. Bron (Plenum, New York, 1985), p. 395
4. M. Born, Th von Kármán, Phys. Zeit. 13, 297 (1912)
5. M. Born, K. Huang, Dynamical Theory of Crystal Lattices (Oxford University Press, London, 1954)