Looking for a free Calculus book? Check this out!

[Bitter]

Here! Have a free Calculus book http://www.math.wisc.edu/~keisler/calc.html

 

[Bitter]

Oh yes and these too!

http://www.math.gatech.edu/~cain/textbooks/onlinebooks.html

 

[Daverz]

Here! Have a free Calculus book http://www.math.wisc.edu/~keisler/calc.html

This one is pretty famous for introducing non-standard calculus using the hyperreal numbers. Apparently there is https://www.amazon.com/gp/product/0521624010/?tag=pfamazon01-20.