Banakh, Taras, Oleksandr Petrenko, Igor Protasov, and Sergiy Slobodianiuk. “Kaleidoscopical Configurations in $G$-Spaces”. The Electronic Journal of Combinatorics 19, no. 1 (January 6, 2012): P12. Accessed March 28, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v19i1p12.