MOGILEVSKII, V. I. Characteristic matrices and spectral functions of first order symmetric systems with maximal deficiency index of the minimal relation. Methods of Functional Analysis and Topology, [S. l.], v. 21, n. 1, p. 76–98, 2015. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/602. Acesso em: 16 dec. 2025.