“…As is known, fractional differential equations have been paid special attention by many researchers for the reason that they serve as an excellent tool for wide applications in various disciplines of science and engineering such as mechanics, electricity, chemistry, and control theory; for more details, we refer to books [1][2][3]. In recent years, there have been a large number of papers dealing with the existence of solutions of nonlinear initial (boundary) value problems of fractional differential equations by using some techniques of nonlinear analysis, such as fixed-point results [4][5][6][7][8][9][10][11][12][13], iterative methods [14][15][16][17][18][19][20][21][22][23], the topological degree [24][25][26][27][28][29], the Leray-Schauder alternative [30,31], and stability [32].…”