Hanna G, Dragomir SS, Cerone P. A general Ostrowski type inequality for double integrals. Tamkang J. Math. [Internet]. 2002 Dec. 31 [cited 2024 Apr. 25];33(4):319-34. Available from: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/280