These are my personal lecture notes, that I prepared for my personal
use as part of the preparations for teaching this module. I post them
here for the sole purpose of assisting the students learning this fascinating, yet difficult subject.
I make no claim of originality. I am basing a large part of the text on the textbooks by F. Chen and A. Piel. Other resources I used are the lecture notes by Richard Fitzpatrick which are available here, and the books by R.M. Kulsrud. Special thanks to Dr. Antoine Bret.