Milovanović, I. Ž., J. E. Pečarić, N. M. Stojanović, and B. A. Mesihović. “On Some Characteristics of Generalized Convex Sequences”. Anal. Numér. Théor. Approx., vol. 17, no. 2, Aug. 1988, pp. 153-6, https://ictp.acad.ro/jnaat/journal/article/view/1988-vol17-no2-art8.