PACHPATTE, B. G. On some fundamental finite difference inequalities. Tamkang Journal of Mathematics, [S. l.], v. 32, n. 3, p. 217–223, 2001. DOI: 10.5556/j.tkjm.32.2001.377. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/377. Acesso em: 20 apr. 2024.