SINAISKY, E. S. Approximation method in one boundary problem with partial derivatives . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 42, n. 6, p. 812–816, 1990. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8842. Acesso em: 6 dec. 2025.