Thuần H, Giao HTL. Discuss with properties a P.F. should posses and what constitutes a resonable extension of an operator relative to a given P. E. JCC [Internet]. 2012 Jul. 27 [cited 2024 Nov. 22];19(4):359-65. Available from: https://vjs.ac.vn/index.php/jcc/article/view/1544