Dovermann's book is interesting, but unfortunately it is incomplete and still relies on limit theory. He explains the Lipschitz condition, which uses the methods of real analysis (i.e. limits) to establish the general method.
My new calculus does not use any of the theory of real analysis. I have also shown that Cauchy's definition of the derivative is a fake and explain why it works.
Limits are not the reason calculus works and are not required at all in any mathematics.
To read about the new calculus visit:
http://thenewcalculus.weebly.com