1. B. Ross (1994). "Fractional Calculus and its Applications,"(Springer, West Haven ) vol.457.
2. I. Podlubny, "Fractional Differential Equations,"(Academic Press, New York) vol.198 (1999).
3. S. G. Samko, A. A. Kilbas and O I. marichev, "Fractional Integrals and Derivatives,"(Gordon and Breach Science Publishers, Switzerland) vol.1 (1993).
4. A new definition of fractional derivative
5. On conformable fractional calculus