SJÖGREN, Rickard. On the Regularity of Graded $k$-Algebras of Krull Dimension $\leqq 1$. Mathematica Scandinavica, Berkeley, CA, United States, v. 71, p. 167–172, 1992. DOI: 10.7146/math.scand.a-12419. Disponível em: https://journals.msp.org/mscand/article/view/1229. Acesso em: 24 jul. 2026.