CHENG, S. S.; XIE, S.-L.; ZHANG, B.-G. QUALITATIVE THEORY OF PARTIAL DIFFERENCE EQUATIONS (II): OSCILLATION CRITERIA FOR DIRECT CONTROL SYSTEMS IN SEVERAL VARIABLES. Tamkang Journal of Mathematics, [S. l.], v. 26, n. 1, p. 65–79, 1995. DOI: 10.5556/j.tkjm.26.1995.4380. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4380. Acesso em: 24 apr. 2024.