1. R. M. Brissey, H. A. Liebhafsky, and H. G. Pfeiffer, ASTM Special Technical Publication, No. 157, 1954, p. 50.
2. K. F. J. Heinrich and T. D. McKinley, Paper presented at the Pittsburgh Conference on Analytical Chemistry, March, 1959.
3. N. Parrish, Philips Technical Review, Vol. 17, No. 7–8, Jan., 1956, p. 206.
4. O. L. Davies, Statistical Methods in Research and Production, Chapter 4; Hafner Publishing Co., New York, 1957.