Shapovalov, Yu.     Frequency symbolic analysis of linear periodically time-variable circuits with many parametric elements [Текст] / Yu. Shapovalov, B. Mandziy // Computational problems of electrical engineering and advanced methods of the theory of electrical engineering. CPEE-AMTEE 2013 : joint conf., Sept. 4-6 2013, Roztoky u Krivoklatu, Czech Republic / Fac. of Electrical of Engineering, Univ. of West Bohemia, Dep. of Theory of Electrical Engineering. — Pilsen : Publ. by the Univ. of West Bohemia in Pilsen, 2013. — P. II-5.