Шаповалов, Ю., and Д. Смаль. “The Results of the Assessment of Stability of Linear Parametric Systems by Three Methods”. Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia, no. 49, Feb. 2012, pp. 52-57, doi:10.20535/RADAP.2012.49.52-57.