Correctness of the Dirichlet and Poincare problems for a multivariate Gellerstedt equation. Neliniini Kolyvannya, [S. l.], v. 15, n. 3, p. 422–426, 2012. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/662. Acesso em: 21 jan. 2026.