CHENG, S. S.; ZHANG, B.-G. QUALITATIVE THEORY OF PARTIAL DIFFERENCE EQUATIONS (I): OSCILLATION OF NONLINEAR PARTIAL DIFFERENCE EQUATIONS. Tamkang Journal of Mathematics, [S. l.], v. 25, n. 3, p. 279–288, 1994. DOI: 10.5556/j.tkjm.25.1994.4455. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4455. Acesso em: 2 may. 2024.