DRAGOMIR, S. S. Inequalities for orthornormal families of vectors in inner product spaces related to Buzano’s, Richard’s and Kurepa’s results. Tamkang Journal of Mathematics, [S. l.], v. 37, n. 3, p. 227-235, 2006. DOI: 10.5556/j.tkjm.37.2006.168. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/168. Acesso em: 12 may. 2021.