  This text is a slightly edited version of lecture notes for a course I gave
at ETH, during the Summer term 2001, to undergraduate Mathematics and Physics
students. It covers a few selected topics from perturbation theory at an
introductory level. Only certain results are proved, and for some of the most
important theorems, sketches of the proofs are provided.
  Contents:
  Chapter 1 - Introduction and Examples
  Chapter 2 - Bifurcations and Unfolding
  Chapter 3 - Regular Perturbation Theory
  Chapter 4 - Singular Perturbation Theory
