THANDAPANI, E.; MAHALINGAM, K. Necessary and sufficient conditions for oscillation of second order neutral difference equations. Tamkang Journal of Mathematics, [S. l.], v. 34, n. 2, p. 137–146, 2003. DOI: 10.5556/j.tkjm.34.2003.260. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/260. Acesso em: 6 jul. 2022.