“…The area of fractional differential equations is now considered to be very important due to its various applications in different fields of science and technology such as control theory, rheology, signal processing, modelling, fractals, chaotic dynamics, bioengineering and biomedical and so on, for example see [6,13,17] and the references therein. Recently, many researchers studied the fractional differential and integro-differential equations and obtained many interesting existence and uniqueness results, see [3,7,12,18,20,19,21,22,23] and the references therein.…”