Thuần, Hồ, and Hoàng Thị Lan Giao. 2012. “Discuss With Properties a P.F. Should Posses and What Constitutes a Resonable Extension of an Operator Relative to a Given P. E”. Journal of Computer Science and Cybernetics 19 (4):359-65. https://doi.org/10.15625/1813-9663/19/4/1544.