R. I. Abdulganiy, O. A. Akinfenwa, A. K. Osunkayode, and S. A. Okunuga, “A HIGHER ORDER TRIGONOMETRICALLY-FITTED METHOD FOR SECOND ORDER NONLINEAR PERIODIC PROBLEMS”, J. Fundam. Appl. Sci., vol. 13, no. 2, pp. 1056–1078, Apr. 2021.