1. W. G. Cady, “Piezoelectricity”, McGraw Hill Book Co., New York, N.Y., (1946), pgs. 510–653.
2. W. P. Mason, “Piezoelectric Crystals and their Applications to Ultrasonics”, D. Van Nostrand Co. New York, N.Y. (1950), pgs. 114–136.
3. F. Jona and G. Shirane, “Ferroelectric Crystals”, Pergamon Press Inc., New York, N.Y. (1962), Pgs. 280–317.
4. H.D. Megaw, “Ferroelectricity in Crystals”, Methuen Co. Ltd., London, England, (1957), pgs. 27.
5. A. R. Ubbelohde and I Woodward, Proc. Roy. Soc. (London), A185, 448–465, (1946).