GHARIB, G. M. The necessary and sufficient conditions for the solutions of elliptic problems. JOURNAL OF SOCIAL SCIENCE RESEARCH, [S. l.], v. 4, n. 2, p. 521–532, 2013. DOI: 10.24297/jssr.v2i3.3144. Disponível em: https://rajpub.com/index.php/jssr/article/view/3144. Acesso em: 6 may. 2024.