Bozhok RV, Koshmanenko VD. Singular Perturbations of Self-Adjoint Operators Associated with Rigged Hilbert Spaces. Ukr. Mat. Zhurn. [Internet]. 2005May25 [cited 2024May6];57(5):622–632. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3628