GRIPENBERG, Gustaf. Volterra integral operators and logarithmic convexity. Mathematica Scandinavica, Berkeley, CA, United States, v. 50, p. 209–220, 1982. DOI: 10.7146/math.scand.a-11955. Disponível em: https://journals.msp.org/mscand/article/view/1691. Acesso em: 25 jul. 2026.