“…Later, the case of Carathéodory system(ODEs) with discontinuous upper and lower solutions were studied(see [12,13,15] for details). Most recently, functional boundary value problems for ODEs and periodic boundary value problems for FDEs have been considered and more general existence results were obtained by S. Heikkiä, A. Cabada, V. Lakshmikantham, R. L. Pouso, W. Ding, J. J. Nieto, R. X. Liang, and others(see [2][3][4][5][7][8][9]11,14,16,[19][20][21]). We also want to point out that the method of upper and lower solutions has also succeeded in solving periodic(or multi-point) boundary value problems for impulsive FDEs(see [3][4][5]7,11,14,19]).…”