Prereq. : Varies. But, I guess some amount of “math-maturity” and interest can take one far. 😉

Link :

Some good mathematical books written by sternberg. The books available are

* Theory of Functions of real variable (2 Meg PDF)
* Advanced Calculus (58 Meg PDF)
* Dynamical systems (1 Meg PDF)
* Lie Algebras (900 K PDF)
* Geometric Asymptotics (AMS Books online)
* Semiriemannian Geometry (1 Meg PDF)

And over here, you can see a list with names of many math books.