Necessary conditions for existence of positive solutions of second order linear difference equations and sufficient conditions for oscillation of solutions. Neliniini Kolyvannya, [S. l.], v. 12, n. 2, p. 180–194, 2009. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/519. Acesso em: 21 jan. 2026.