Command Reference : Operator and Function Reference : References
Abramowitz, M. and I. A. Stegun (1964). Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, New York: Dover Publications.
Press, W. H., S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery (1992). Numerical Recipes in C, 2nd edition, Cambridge University Press.
Temme, Nico M. (1996). Special Functions: An Introduction to the Classical Functions of Mathematical Physics, New York: John Wiley & Sons.