The authors present the greatest value and the least value such that the double inequality holds for all with , where and denote the Seiffert and pth one-parameter means of two positive numbers a and b, respectively.
Hua-Nan Hu. Guo-Yan Tu. Yu-Ming Chu. "Optimal Bounds for Seiffert Mean in terms of One-Parameter Means." J. Appl. Math. 2012 1 - 7, 2012. https://doi.org/10.1155/2012/917120