Kolczyńska-Przybycień, Kinga, and Hubert Przybycień. “A Note on Cancellation Law for P-Convex Sets”. New Zealand Journal of Mathematics 49 (December 31, 2019): 11–13. Accessed March 29, 2024. https://nzjmath.org/index.php/NZJMATH/article/view/26.