  We study this subject by first proving that the p-primary subgroup of the
classical Selmer group for an elliptic curve with good, ordinary reduction at a
prime p has a very simple and elegant description which involves just the
Galois module of p-power torsion points. We then prove theorems of Mazur,
Schneider, and Perrin-Riou on the basis of this description. The final section,
which is half of this long paper, contains a number of results and examples
including a thorough study of the mu-invariant.
