ACU, Ana Maria, and Heiner GONSKA. “Weighted Ostrowski-Grüss Type Inequalities”. Studia Universitatis Babeș-Bolyai Mathematica, vol. 60, no. 2, June 2015, pp. 183-92, https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/5716.