NENOV, N. A GENERALIZATION OF A RESULT OF DIRAC. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 95, p. 59–69, 2003. Disponível em: https://ftl5.uni-sofia.bg./index.php/fmi/article/view/176. Acesso em: 24 nov. 2024.