Sơn, T. T., Đỗ N. Tiến, and P. Đình Phong. “Asssociate Rull Using Heldge Algebra Approach”. Journal of Computer Science and Cybernetics, vol. 27, no. 4, May 2012, pp. 341-52, doi:10.15625/1813-9663/27/4/598.