Klyushin, D., and Ya. Shtyk. “CLASSIFICATION OF MULTIVARIATE SAMPLES USING PETUNIN ELLIPSES”. Journal of Numerical and Applied Mathematics, no. 1 (133) (July 2, 2020): 59-67. Accessed November 18, 2025. https://jnam.knu.ua/index.php/jnam/article/view/85.