Free On-Line Calculus Text

A free calculus textbook, “Elementary Calculus:  An Infinitesimal Approach” is available for download here:

http://www.math.wisc.edu/~keisler/calc.html

The book, written by the University of Wisconsin’s Jerome Keisler, seems to take an advanced and rigorous approach to the topic, beginning with an introduction to real and hyperreal numbers (hence the “Infinitesimal Approach”).

The fourteen chapters include the standard Calculus topics, and also multivariable and vector calculus topics such as Vectors and Partial Derivatives.  Every chapter has multiple sets of exercises.

This is a nice resource for the Calculus teacher or the advanced student looking for a rigorous approach to Calculus.