Sơn, Trần Thái, and Nguyễn Thế Dũng. “A New Method for Solving the Fuzzy Model Problem Base on Hedge Algebra”. <i>Journal of Computer Science and Cybernetics</i>, vol. 21, no. 3, July 2012, pp. 248-60, doi:10.15625/1813-9663/21/3/1249.