1. K. William andE. Warnke, in Proceedings, Seminar of Concrete Structures Subjected to Triaxial Stresses; Paper III-7, Bergamo, Italy, May 1974, International Association of Bridge and Structural Engineerings, 1975).
2. J. Wastiels, International Association of Bridge and Structural Engineers, Report of the Working Commission, Vol. 29, Technical University of Denmark, 1978?1979.
3. J. Wastiels, International Report, Vrije University Brussels, Pleinlaan 2, B-1050, Brussels, Belgium, 1981.
4. M. D. Kotsovos,Mag. Concrete Res. 31 (1979) 151.
5. G. F. Smith andR. S. Rivlin,Trans. Am. Math. Soc. 88 (1958) 175.