2 citations to https://www.mathnet.ru/eng/pa189

1. Feng Qi, Mansour Mahmoud, “Bounding the gamma function in terms of the trigonometric and exponential functions”, Acta Sci. Math., 83:1-2 (2017), 125  
2. F. Qi, B. N. Guo, “Remarks on complete monotonicity of a function involving the Gamma function”, Probl. anal. Issues Anal., 4(22):1 (2015), 66–72