Akhmetov, M.U. and Perestyuk, N.A. (1993) “On a comparison method for pulse systems in the space $R^n$”, Ukrains’kyi Matematychnyi Zhurnal, 45(6), pp. 753–762. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5864 (Accessed: 10 April 2025).