Yeshkeyev, A.R., A.R. Yarullina, and S.M. Amanbekov. “On Categoricity Questions for Universal Unars and Undirected Graphs under Semantic Jonsson Quasivariety”. Bulletin of the Karaganda University. Mathematics Series 111, no. 3 (September 30, 2023): 165–180. Accessed July 10, 2025. http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/591.