KANKAANRINTA, Marja. On Embeddings of Proper Smooth $G$-Manifolds. Mathematica Scandinavica, Berkeley, CA, United States, v. 74, p. 208–214, 1994. DOI: 10.7146/math.scand.a-12490. Disponível em: https://journals.msp.org/mscand/article/view/1137. Acesso em: 25 jul. 2026.