RIIBER, Agot E. Über die $\alpha$-Kapazität einer verallgemeinerten Cantorschen Punktmenge. Mathematica Scandinavica, Berkeley, CA, United States, v. 16, p. 33–37, 1965. DOI: 10.7146/math.scand.a-10745. Disponível em: https://journals.msp.org/mscand/article/view/2580. Acesso em: 25 jul. 2026.