BozhokR. V. and KoshmanenkoV. D. (2005) “Singular Perturbations of Self-Adjoint Operators Associated with Rigged Hilbert Spaces”, Ukrains’kyi Matematychnyi Zhurnal, 57(5), pp. 622–632. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3628 (Accessed: 24November2024).