Boundary-value Problems for Integro-differential Equations of Elliptic Type. Journal of Partial Differential Equations, [S. l.], v. 3, n. 1, p. 81–89, 1990. Disponível em: https://www.global-sci.com/index.php/jpde/article/view/3653. Acesso em: 27 feb. 2026.