Two sharp inequalities for bounding the Seiffert mean by the arithmetic,   centroidal, and contra-harmonic means
  In the paper, the authors find the best possible constants appeared in two inequalities for bounding the Seiffert mean by the linear combinations of the arithmetic, centroidal, and contra-harmonic means. 
Wei-Dong Jiang, Jian Cao, and Feng Qi
math.CA