HANNA, G.; DRAGOMIR, S. S.; CERONE, P. A general Ostrowski type inequality for double integrals. Tamkang Journal of Mathematics, [S. l.], v. 33, n. 4, p. 319–334, 2002. DOI: 10.5556/j.tkjm.33.2002.280. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/280. Acesso em: 19 aug. 2022.