WEIER, Josef. Invariante Schnittsysteme stetiger Transformationen. Mathematica Scandinavica, Berkeley, CA, United States, v. 7, p. 33–48, 1959. DOI: 10.7146/math.scand.a-10559. Disponível em: https://journals.msp.org/mscand/article/view/2785. Acesso em: 8 sep. 2026.