1. Bairamov, E., Öztürk Mert, R., Ismailov, Z. I., Selfadjoint extensions of a singular differential operator, J. Math. Chem., 50 (2012), 1100-1110.
2. Fischbacher, C., On the theory of dissipative extensions. PhD, University of Kent School of Mathematics, Statistic and Actuarial Science, Canterbury, England, 2017.
3. Gorbachuk, V. I., Gorbachuk, M. L., Boundary Value Problems for Operator Differential Equations, Dordrecht, the Netherlands, Kluwer Academic Publishers, 1991.
4. Hörmander, L., On the theory of general partial differential operators, Acta Mathematica, 94 (1955), 161-248.
5. Ismailov, Z. I., Ipek, P., Selfadjoint singular differential operators of first order and their spectrum, Electronic Journal of Differential Equations, 21 (2016), 1-9.