1. Akhiezer, N.I., Glazman, M.: Theory of Linear Operators in Hilbert Space, vol. I. Monograph Studies in Mathematics, vol. 9. Pitman, Boston (1981)
2. Akhiezer, N.I., Glazman, M.: Theory of Linear Operators in Hilbert Space, vol. II. Monograph Studies in Mathematics, vol. 10. Pitman, Boston (1981)
3. Arlinskii, Yu.M., Derkach, V.A., Tsekanovskii, E.R.: On unitary equivalent quasi-Hermitian extensions of Hermitian operators. Mat. Fiz. 29, 72–77 (1981) (in Russian)
4. Birman, M.S., Solomjak, M.Z.: Spectral Theory of Self-Adjoint Operator in Hilbert Space. D. Reidel Publishing Company, Dordrecht (1987)
5. Gawlik, M., Główczyk, A., Kuzhel, S.: On the Lax–Phillips scattering matrix of the abstract wave equation. Banach J. Math. Anal. 13, 449–467 (2019)