An application of Hayashi's inequality for differentiable functions
It is shown that Iyengar's inequality [\textit{K. S. K. Iyengar}, Math. Stud. 6, 75-76 (1938)] can be obtained from the well-known generalization of Steffensen's inequality for monotone functions obtained by \textit{T. Hayashi} [Tôhoku Math. J. 15, 236-239 (1919; JFM 47.0222.03)].
scientific article; zbMATH DE number 950622