1. Aczél, J.,Lectures on functional equations and their applications. Academic Press, New York, 1966.
2. Davison, T. M. K.,The definition of quadratic forms. Math. Report No. 91, May, 1977, McMaster University.
3. Gould, H. W.,Combinatorial identities. Revised Edition, Gould Publications, Morgantown, W. Va., 1972.
4. Greub, W. H.,Linear algebra. 3rd Ed., Springer, Berlin, New York, 1967.
5. Herstein, I. N.,Topics in algebra. Second Ed., Xerox College Publishing, Lexington, Mass., 1975.