HWANG, D.-Y.; YANG, G.-S. Pre-Gr"uss type inequalities in $ 2 $-inner product spaces. Tamkang Journal of Mathematics, [S. l.], v. 38, n. 3, p. 191–204, 2007. DOI: 10.5556/j.tkjm.38.2007.71. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/71. Acesso em: 25 apr. 2024.