1. W.A. Coppel, “J.B. Fourier—On the Occasion of his Two Hundredth Birthday.” American Mathematical Monthly, 76, 1969.
2. Philip Davis, “Leonard Euler’s Integral: A Historical Profile of the Gamma Function.” American Mathematical Monthly, December, 1959.
3. Peter Duren, Invitation to Classical Analysis. John Wiley and Sons, New York, 2012.
4. David Fowler, “A Simple Approach to the Factorial Function.” The Mathematical Gazette, vol. 80, July 1996.