HILLE, Einar. Some extremal properties of Laplace transforms . Mathematica Scandinavica, Berkeley, CA, United States, v. 1, p. 227–236, 1953. DOI: 10.7146/math.scand.a-10381. Disponível em: https://journals.msp.org/mscand/article/view/2942. Acesso em: 25 jul. 2026.