TSVETKOV, E. L. On regularity of generalized solutions of the third boundary-value problem for an elliptic difference-differential equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 47, n. 1, p. 93–104, 1995. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5386. Acesso em: 5 dec. 2025.