1.
Gorbachuk VI, Gorbachuk ML. Theory of self-adjoint extensions of symmetric operators. entire operators and boundary-value problems. Ukr. Mat. Zhurn. [Internet]. 1994Feb.25 [cited 2024Jul.27];46(1-2):55–62. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5769