Pečarić, J. E., and M. V. Jovanović. “Some Inequalities for \(\alpha\)-Convex Functions”. Anal. Numér. Théor. Approx., vol. 19, no. 1, Feb. 1990, pp. 67-70, https://ictp.acad.ro/jnaat/journal/article/view/1990-vol19-no1-art11.