MOGILEVSKII, V. I. Symmetric extensions of symmetric linear relations (operators) preserving the multivalued part. Methods of Functional Analysis and Topology, [S. l.], v. 24, n. 2, p. 152–177, 2018. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/692. Acesso em: 15 dec. 2025.