CeroneP., DragomirS. S., and KikiantyE. “Jensen – Ostrowski Inequalities and Integration schemes via the Darboux Expansion”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 69, no. 8, Aug. 2017, pp. 1123-40, http://umj.imath.kiev.ua/index.php/umj/article/view/1763.