DUDLEY, R. M. On second derivates of convex functions. Mathematica Scandinavica, Berkeley, CA, United States, v. 41, p. 159–174, 1977. DOI: 10.7146/math.scand.a-11710. Disponível em: https://journals.msp.org/mscand/article/view/1938. Acesso em: 25 jul. 2026.