SONG, C. Positive solutions of boundary value problems for $ p $-Laplacian functional difference equations. Tamkang Journal of Mathematics, [S. l.], v. 38, n. 4, p. 291-299, 2007. DOI: 10.5556/j.tkjm.38.2007.62. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/62. Acesso em: 3 dec. 2021.