Other interesting open-source calculus texts:<p>(1) Corral, M. (super-readable!)<p><a href="http://www.mecmath.net/calculus/index.html" rel="nofollow">http://www.mecmath.net/calculus/index.html</a>
<a href="http://www.mecmath.net/index.html" rel="nofollow">http://www.mecmath.net/index.html</a><p>(2) Feldman et al.<p><a href="http://www.math.ubc.ca/~CLP/" rel="nofollow">http://www.math.ubc.ca/~CLP/</a>