BISTRÖM, P.; JARAMILLO, Jesus A. $C^\infty$-Bounding Sets and Compactness. Mathematica Scandinavica, Berkeley, CA, United States, v. 75, p. 82–86, 1994. DOI: 10.7146/math.scand.a-12504. Disponível em: https://journals.msp.org/mscand/article/view/1169. Acesso em: 24 jul. 2026.