Grinis, Irus, Feliksas Ivanauskas, and Gediminas Stepanauskas. “Some Geometric Aspects of Polyvalent Systems Modeling”. Lietuvos matematikos rinkinys 53, no. B (December 25, 2012): 62–67. Accessed July 18, 2024. https://www.journals.vu.lt/LMR/article/view/17091.