AL-KHARSANI, H. A.; AL-AREEFI, N. M. Sandwich-type theorems for certain integral operators. Tamkang Journal of Mathematics, [S. l.], v. 41, n. 3, p. 207–216, 2010. DOI: 10.5556/j.tkjm.41.2010.721. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/721. Acesso em: 20 apr. 2024.