HWANG, S.-R.; HO, M.-I. On discrete inequalities of Gr"{u}ss type. Tamkang Journal of Mathematics, [S. l.], v. 35, n. 3, p. 213-218, 2004. DOI: 10.5556/j.tkjm.35.2004.201. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/201. Acesso em: 3 dec. 2021.