The Klein-Gordon Field - A brief overview of the lagrangian for a Klein-Gordon field, by Professor John Norbury.
The Quantum Theory of Particles - 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.
Relativistic quantum mechanics - An electronic textbook for relativistic quantum mechanics is presented. It can be ordered free
Selected Papers on Geometric Algebra in Quantum Mechanics - 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