FAROUGHI, M. H. Operator-valued integral of vector-function and bases. Methods of Functional Analysis and Topology, [S. l.], v. 13, n. 4, p. 318–328, 2007. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/359. Acesso em: 16 dec. 2025.