Molyboga, V. M., and V. A. Mikhailets. “Remarks on Schrödinger Operators With Singular Matrix Potentials”. Methods of Functional Analysis and Topology 19, no. 2 (June 25, 2013): 161–167. Accessed December 18, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/543.