“…As result, we conclude that if 𝜎 and 𝜌 are taken from conditions 𝜎 > max(𝜎 1 , 𝜎 2 , 𝜎 3 , 𝜎 4 , 𝜎 5 , 𝜎 6 ) and 𝜌 ∈ (0, min(𝜌 1 , 𝜌 2 , 𝜌 3 , 𝜌 4 )), then the operator A carries out contracting mapping the ball S(g 0 , 𝜌) into itself, and according to Banach theorem in this ball, it has a unique fixed point; that is, there exists a unique solution of operator Equation (18). The proof of the theorem is complete.…”