Li, Ai-Jun, and Chao-Ping Chen. “Logarithmically Complete Monotonicity Properties and Characterizations of the Gamma Function”. Tamkang Journal of Mathematics 38, no. 4 (December 31, 2007): 313–322. Accessed April 16, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/65.