Lectures on Gravitational Lensing
  These lectures give an introduction to Gravitational Lensing. We discuss lensing by point masses, lensing by galaxies, and lensing by clusters and larger-scale structures in the Universe. The relevant theory is developed and applications to astrophysical problems are discussed. 
Ramesh Narayan (1) and Matthias Bartelmann (2) ((1) CfA, (2) MPA)