1. W.P. Manson: J. Acoust. Soc. Am 70, 1561 (1981)
2. W. Voigt: Lehrbuch der Kristallphysik ( Teubner, Leipzig 1910 )
3. J.F. Nye: Physical Properties of Crystals ( Clarendon, Oxford 1957 ) p. 110
4. W.G. Cady: Piezoelectricity ( Dover, New York 1964 )
5. W.P. Warren: Piezoelectric Crystals and their Applications to Ultrasonics ( Van Nostrand, Toronto 1950 )