ALBRECHT, F.; DIAMOND, H. G. An Extremal Problem Involving Functions and Their Inverses. Mathematica Scandinavica, Berkeley, CA, United States, v. 29, p. 328–336, 1971. DOI: 10.7146/math.scand.a-11059. Disponível em: https://journals.msp.org/mscand/article/view/2295. Acesso em: 25 jul. 2026.