VLADIMIRSKIJ, J. On the theory of semi-fredholm graphs in topological linear spaces. Lithuanian Mathematical Journal, [S. l.], v. 10, n. 1, p. 17–28, 1970. DOI: 10.15388/LMJ.1970.20833. Disponível em: https://www.journals.vu.lt/LMJ/article/view/20833.. Acesso em: 5 may. 2024.