1. V. I. Gorbachuk and M. L. Gorbachuk, Boundary Value Problems for Operator Differential Equations, 1st ed. (Kluwer Academic, Dordrecht, the Netherlands, 1991).
2. J. von Neumann, ‘‘Allgemeine eigenwerttheories hermitescher funktionaloperatoren,’’ Math. Ann. 102, 49–131 (1929–1930).
3. C. Fischbacher, ‘‘On the theory of dissipative extensions,’’ PhD Thesis (Univ. of Kent School of Mathematics, Canterbury, UK, 2017).
4. B. Sz. Nagy and C. Foias, Analyse Harmonique des Operateurs de L’espace de Hilbert (Akadémiai Kiadó, Budapest, Paris, 1967).
5. F. S. Rofe-Beketov and A. M. Kholkin, Spectral Analysis of Differential Operators, Vol. 7 of World Scientific Monograph Series in Mathematics (World Scientific, Singapore, 2005).