. "AN APPROXIMATE SOLUTION OF SYSTEMS OF HIGH-ORDER LINEAR DIFFERENTIAL EQUATIONS WITH VARIABLE COEFFICIENTS BY MEANS OF A RATIONAL CHEBYSHEV COLLOCATION METHOD Vol. 4(1) Jan. 2016, No. 8, pp. 86-98 MOHAMED A. RAMADAN, KAMAL. R. RASLAN, MAHMOUD A. NASSAR", Electronic Journal of Mathematical Analysis and Applications, 4, 1, 2016, -. doi: 10.21608/ejmaa.2016.310815