Ramanujan's cubic transformation inequalities for zero-balanced   hypergeometric functions
  In this paper, a generalization of Ramanujan's cubic transformation, in the form of an inequality, is proved for zero-balanced Gaussian hypergeometric function $F(a,b;a+b;x)$, $a,b>0$. 
Miao-Kun Wang, Yu-Ming Chu and Ye-Ping Jiang
math.CA