1. Y.S. Hong, R.F. Williamson, and W.O.J. Boo, J. Chem. Ed.,57, 583 (1980).
2. R.F. Williamson, and W.O.J. Boo, Inorg. Chem.,16, 646 (1977).
3. J.C. Cousseins and A. de Kozak, C.R. Acad. Sci.,263, 1533 (1966).
4. L. Pauling, Acta. Cryst.,51, 1010 (1929).
5. R. Williams, “The Geometrical Foundation of Natural Structure”, Dover, New York (1972).