1. W. G. Cady,Piezoelectricity(McGraw-Hill Book Company, Inc., New York, 1946), pp. 444–459.
2. R. A. Heising, Editor,Quartz Crystals for Electrical Circuits(D. Van Nostrand Company, Inc., Princeton, New Jersey, 1946).
3. P. Vigoreux and C. F. Booth,Quartz Vibrators and Their Applications(H. M. Stationery Office, London, 1950).
4. The crystals used in this work were obtained from the James Knight Company, Sandwich, Illinois.
5. A. W. Warner, Bell System Monograph 3297.