BARKOVSKY, V. V. On Green’s function of a self-conjugate elliptical operator generated by a differential expression and inhomogeneous boundary value conditions . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 2, p. 84–91, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8718. Acesso em: 6 dec. 2025.