WERNER, Dirk. The Perfekt theory of $M$-ideals. Mathematica Scandinavica, Berkeley, CA, United States, v. 128, n. 2, 2022. DOI: 10.7146/math.scand.a-132230. Disponível em: https://journals.msp.org/mscand/article/view/111. Acesso em: 24 jul. 2026.