“…Fractional calculus is an excellent tool for the description of the process of mathematical analysis in various areas of finance, physical systems, control systems and mechanics, and so forth [1][2][3][4][5]. Many methods are used to study various fractional differential equations, such as fixed point index theory [6], iterative method [7][8][9], theory of linear operator [10,11] sequential techniques, and regularization [12], fixed point theorems [13][14][15][16][17], the Mawhin continuation theorem for resonance [18][19][20][21][22], the variational method [23]. The definition of the fractional order derivative used in the aforementioned results is either the Caputo or the Riemann-Liouville fractional order derivative.…”