HANSEN, Henry W. On the Gaussian Markoff spectrum. MATHEMATICA SCANDINAVICA, [S. l.], v. 43, p. 35–43, 1978. DOI: 10.7146/math.scand.a-11760. Disponível em: https://tidsskrift.dk/math/article/view/11760. Acesso em: 14 aug. 2026.