YUSENKO, A. A.; RABANOVICH, V. I. On decompositions of the identity operator into a linear combination of orthogonal projections. Methods of Functional Analysis and Topology, [S. l.], v. 16, n. 1, p. 57–68, 2010. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/440. Acesso em: 16 dec. 2025.