Leonov, G. A., V. B. Smirnova, and L. Sperling. “A Frequency-Domain Criterion for Global Stability of Systems With Angular Coordinates”. Technische Mechanik - European Journal of Engineering Mechanics 17, no. 3 (October 13, 2019): 223–229. Accessed November 22, 2024. https://journals.ub.ovgu.de/index.php/techmech/article/view/1202.