“…We set dx dt = 0, dy dt = 0, and dz dt = 0, and according to Equation ( 13), we obtained nine equilibrium points of this system:E 1 (0, 0, 0), E 2 (0, 0, 1), E 3 (0, 1, 0), E 4 (0, 1, 1), E 5 (1, 0, 0), E 6 (1, 0, 1), E 7 (1, 1, 0), E 8 (1, 1, 1), E 9 (x * , y * , z * ). If, and only if, x * ∈ [0, 1], y * ∈ [0, 1], and z * ∈ [0, 1], then E 9 (x * , y * , z * ), according to Equation (14), is an equilibrium point.…”