Notes by Eric Poisson providing two derivations of the Lorentz--Dirac equation.

An electronic textbook for relativistic quantum mechanics is presented. It can be ordered free

These papers analyze the quantum mechanical Dirac theory of the electron with respect to its geometric structure as revealed by reformulation in terms of Spacetime Algebra

A brief overview of the lagrangian for a Klein-Gordon field, by Professor John Norbury.

A new approach to relativity, quantum mechanics, and field theory which solves many old puzzles, such as ultraviolet infinities and superluminal spreading of wave packets.