LIU, Z. A simple proof of the discrete Steffensen’s inequality. Tamkang Journal of Mathematics, [S. l.], v. 35, n. 4, p. 281–283, 2004. DOI: 10.5556/j.tkjm.35.2004.185. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/185. Acesso em: 6 may. 2024.