V. A. Mikhailets, A. A. Murach, and V. Novikov, “Localization principles for Schrödinger operator with a singular matrix potential”, MFAT, vol. 23, no. 4, pp. 367–377, Dec. 2017, Accessed: Dec. 15, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/677