C. V and B. J. A, “Oscillation Criteria for Generalized First-Order Systems of Linear Difference Equations: u(k+l)= a(k)u+b(k)v,v(k+l)= c(k)u+d(k)v and u(k+l) = a(k)u+b(k)v+f_1 (k)v(k+l) = c(k)u+d(k)v+f_2 (k) where a(k),b(k),c(k),d(k) and f_i (k),i = 1,2 are real valued functions defined for k ≥ 0.”, CM, vol. 3, no. 2, pp. 114-122, Dec. 2019.