Petrov АА, Mikheev РА. Computer Finding of Four-element Multiplicatively Idempotent Semirings. Вест. ПГУ. Мат. Мех. Инф. [Internet]. 2022 Jul. 5 [cited 2025 Apr. 5];(2 (57):46-52. Available from: https://press.psu.ru/index.php/Math/article/view/5321