On the extendibility "to the left" of solutions for a difference equation. Neliniini Kolyvannya, [S. l.], v. 10, n. 3, p. 298–302, 2007. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/438. Acesso em: 21 jan. 2026.