1. K S Miller and B Ross, An introduction to the fractional calculus and fractional differential equations (Wiley, New York, 1993)
2. B J West, M Bolognab and P Grigolini, Physics of fractal operators (Springer, New York, 2003)
3. S G Samko, A A Kilbas and O I Marichev, Fractional integrals and derivatives: Theory and applications (Gordon and Breach, Yverdon, 1993)
4. I Podlubny, Fractional differential equations (Academic Press, San Diego, 1999)
5. M Caputo, J. R. Astron. Soc. 13, 529 (1967)