GRIPENBERG, Gustaf. Volterra integral operators and logarithmic convexity. MATHEMATICA SCANDINAVICA, [S. l.], v. 50, p. 209–220, 1982. DOI: 10.7146/math.scand.a-11955. Disponível em: https://tidsskrift.dk/math/article/view/11955. Acesso em: 14 aug. 2026.