SJÖDIN, G. On Filtered Modules and their Associated Graded Modules. MATHEMATICA SCANDINAVICA, [S. l.], v. 33, p. 229–249, 1973. DOI: 10.7146/math.scand.a-11486. Disponível em: https://www.mscand.dk/article/view/11486. Acesso em: 6 may. 2024.