DRAGOMIR, S.S.; SOFO, A. Lower and upper bounds of the Čebyšev functional for the Riemann-Stieltjes integral. Italian Journal of Pure and Applied Mathematics, [S. l.], v. 28, p. 41–50, 2011. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/6017. Acesso em: 18 jul. 2026.