Calculus: Difference Equations to Differential Equations
math.furman.edu/~dcs/bookCalculus: Difference Equations to Differential Equations. Each section is in PostScript format.If you do not have a PostScript viewer, click here for information on obtaining and installing a PostScript viewer. Chapter 1: Sequences, limits, and difference equations. Section 1.1: Calculus: Areas and tangents (244 kb) Java applet: Area of a circle
Fractional calculus - Wikipedia
https://en.wikipedia.org/wiki/Fractional_calculusThe Fractional Calculus; Theory and Applications of Differentiation and Integration to Arbitrary Order. Mathematics in Science and Engineering. V. Academic Press. ISBN 978-0-12-525550-9. Miller, Kenneth S.; Ross, Bertram, eds. (1993). An Introduction to the Fractional Calculus and Fractional Differential Equations. John Wiley & Sons.