4Abramowitz, M. ,Stegun, C. A. (Eds.). Handbook of MathFunctions with Formulas, Graphs, and Mathematical Tables, 9th printing[ M ]. New York : Dover, 1972 : 17.
5Dickson, L. E. Elementary Theory of Equations [ M ]. New York : Wiley, 1914:36 - 37.
6Spanier, J. , Oldham, K. B. The Cubic Function and Higher Polynomials. Ch. 17 in An Atlas of Functions[ M]. Washington, DC : Hemisphere, 1987 : 131 - 147.
