DAS, G. On Functional Methods. The Journal of the Indian Mathematical Society, [S. l.], v. 31, n. 2, p. 81–93, 1967. DOI: 10.18311/jims/1967/16792. Disponível em: https://www.informaticsjournals.com/index.php/jims/article/view/16792. Acesso em: 7 may. 2024.