Hân, Nguyễn Đình, Hồ Ngọc Vinh, Phạm Trung Huy, and Đỗ Long Vân. 2012. “An Algorithm for Testing Whether a Regular Language Is a Code”. Journal of Computer Science and Cybernetics 27 (1):1-8. https://doi.org/10.15625/1813-9663/27/1/457.