YESHKEYEV, A.R.; ULBRIKHT, O.I.; YARULLINA, A.R. Existentially positive Mustafin theories of S-acts over a group. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 106, n. 2, p. 172–185, 2022. DOI: 10.31489/2022m2/172-185. Disponível em: http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/535. Acesso em: 25 aug. 2025.