Chung, Phan Van, and Duong Tuan Anh. “a Query Sublanguage for Temporal Clinical Database Systems and Its Implementation”. Journal of Computer Science and Cybernetics 21, no. 4 (July 24, 2012): 293–300. Accessed April 28, 2024. https://vjs.ac.vn/index.php/jcc/article/view/1433.