Huy, Phan Trung, and Nguyễn Quý Khang. “Regular Omega-Languages and Finite Monoids Having Infinite Products”. Journal of Computer Science and Cybernetics 19, no. 2 (July 26, 2012): 180–186. Accessed January 14, 2026. https://vjes.vast.vn/jcc/article/view/1512.