KLEPPE, Jan O. Deformations of graded algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 45, p. 205–231, 1979. DOI: 10.7146/math.scand.a-11837. Disponível em: https://tidsskrift.dk/math/article/view/11837. Acesso em: 14 aug. 2026.