1) Brown, C.B. (1978): "The use of maximum entropy in the characterization of granular media," Proc., U.S.-Japan Seminar on Continuum-Mechanical and Statistical Approaches in Mechanics of Granular Material, Sendai, pp.98-108.
2) Field, W.G. (1963): "Towards the statistical definition of a granular mass," Proc., 4th A. and N.Z. Conf. SMFE, pp. 143-148.
3) Harr, M.E. (1977): Mechanics of Particulate Media-A Probabilistic Approach, McGraw-Hill Book Co. Inc., New York, p.28.
5) Ingles, O.G. (1963): "Discussion of 'Towards the statistical definition of a granular mass', by Field, W.G.," Proc., 4th A. and N.Z. Conf. SMFE, p.314.