Ban, Đoàn Văn, Lê Mạnh Thạnh, and Hoàng Bảo Hùng. “The Equivalent Expression Between the OODB Query Language OQL and the Object Algebra”. <i>Journal of Computer Science and Cybernetics</i> 20, no. 3 (July 26, 2012): 257–269. Accessed November 5, 2025. https://jcc.vast.vn/jcc/article/view/1488.