On Iyengar-Type Inequalities via Quasi-Convexity and Quasi-Concavity
  In this paper, we obtain some new estimations of Iyengar-type inequality in which quasi-convex(quasi-concave) functions are involved. These estimations are improvements of some recently obtained estimations. Some error estimations for the trapezoidal formula are given. Applications for special means are also provided. 
M. Emin Ozdemir
math.FA