V. I. Mogilevskii, “Spectral and pseudospectral functions of Hamiltonian systems: development of the results by Arov-Dym and Sakhnovich”, MFAT, vol. 21, no. 4, pp. 370–402, Dec. 2015, Accessed: Dec. 16, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/624