1. Hearmon, R. F. S., An Introduction to Applied Anisotropic Elasticity, 84 (Oxford Univ. Press, 1961).
2. Synge, J. L., J. Math. Phys., 35, 232 (1957).
3. Buchwald, V. T., Quart. J. Mech. and App. Maths. (to be published).
4. Buchwald, V. T., Proc. Roy. Soc., A, 253, 563 (1959).
5. Hearmon, R. F. S. (ref. 1, page 69).