On the basisness in L_2(0,1) of the root functions in not strongly regular boundary value problems. European Journal of Pure and Applied Mathematics, Maryland, USA, v. 1, n. 2, p. 51–60, 2008. Disponível em: https://www.ejpam.com/index.php/ejpam/article/view/115. Acesso em: 21 dec. 2024.