1. Camp, B. H.The mathematical part of elementary statistics. New York: D. C. Heath, 1931. Pp. 300–314.
2. Castellan, N. J., Jr. and Link, S. W. Tetrachoric correlation program for the IBM 709/7090 (CPA 174).Behav. Sci., 1964,9, 292.
3. Kendall, M. G. and Stuart, A.Advanced theory of statistics (Vol. I) (2nd ed.). London: Griffin, 1958.
4. Pearson, K. I. Mathematical contribution to the theory of evolution. VII. On the correlation of characters not quantitatively measurable.Phil. Trans. roy. Soc. London. 1901,195A, 1–47.
5. Walker, H. M. and Lev, J.,Statistical inference. New York: Holt, Rinehart & Winston, 1953. Pp. 271–275.