RABANOVICH, V. I. Banach algebras generated by three idempotents. Methods of Functional Analysis and Topology, [S. l.], v. 4, n. 1, p. 65–67, 1998. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/55. Acesso em: 19 dec. 2025.