Ruận, Đặng Huy, and Vũ Trọng Quế. “The Finite Automates Complexity Degree of a Double-Side Regular Expression”. Journal of Computer Science and Cybernetics 23, no. 2 (June 4, 2012): 128–131. Accessed December 6, 2025. https://vjs.ac.vn/jcc/article/view/940.