Some Hermite-Hadamard type inequalities for the product of two operator   preinvex functions
  In this paper we introduce operator preinvex functions and es- tablish a Hermite-Hadamard type inequality for such functions. We give an estimate of the right hand side of a Hermite-Hadamard type inequality in which some operator preinvex functions of selfadjoint operators in Hilbert spaces are involved. Also some Hermite-Hadamard type inequalities for the product of two operator preinvex functions are given. 
A. G. Ghazanfari, A. Barani
math.FA