ARLINSKII, Yu. M.; KOVALEV, Yu. Factorizations of nonnegative symmetric operators. Methods of Functional Analysis and Topology, [S. l.], v. 19, n. 3, p. 211–226, 2013. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/549. Acesso em: 16 dec. 2025.