[1]
Y. M. Arlinskii and E. Tsekanovskii, “Some remarks on singular perturbations of self-adjoint operators”, MFAT, vol. 9, no. 4, pp. 287–308, Dec. 2003, Accessed: Feb. 04, 2026. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/223