1. Kingsbury, E.F. and Ohl, R.S., Bell Syst. Tech. J. 31, 802 (1952).
2. Ohl, R.S., Bell Syst. Tech. J. 31, 104 (1952).
3. Bragg, V.H., Phil. Mag. 20, 387 (1910)
4. see also Von Laue, M., Historical Introduction to International Tables for X-ray Crystallog. Vol. 1 (1952), by Henry, N.F.M. and Lonsdale, K. (Kynoch Press).
5. Stark, J., Physik. Z. 13, 973 (1912).