VOLKMANN, Lutz. Ganze Funktionen mit negativen Nullstellen. Mathematica Scandinavica, Berkeley, CA, United States, v. 40, p. 143–150, 1977. DOI: 10.7146/math.scand.a-11683. Disponível em: https://journals.msp.org/mscand/article/view/1964. Acesso em: 25 jul. 2026.