VAVRYKOVYCH, L.; SHAPOVALOVA, O.; KUZHEL, S. A. On $J$-self-adjoint extensions of the Phillips symmetric operator. Methods of Functional Analysis and Topology, [S. l.], v. 16, n. 4, p. 333–348, 2010. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/461. Acesso em: 16 dec. 2025.