DAELE, A. Van. On the spectrum of the analytic generator. Mathematica Scandinavica, Berkeley, CA, United States, v. 37, p. 307–318, 1975. DOI: 10.7146/math.scand.a-11609. Disponível em: https://journals.msp.org/mscand/article/view/2062. Acesso em: 25 jul. 2026.