Relativistic

An Introduction to the Lorentz-Dirac Equation
Notes by Eric Poisson providing two derivations of the Lorentz--Dirac equation.
http://arxiv.org/abs/gr-qc/9912045

Publications in Physics and Mathematics by Walter Pfeifer
A textbook for relativistic quantum mechanics with detailed description of the Dirac equation and other publications.
http://www.walterpfeifer.ch/

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.
http://www.geocities.com/meopemuk/

Relativistic quantum mechanics
An electronic textbook for relativistic quantum mechanics is presented. It can be ordered free
http://rel.qm.walterpfeifer.ch

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
http://modelingnts.la.asu.edu/html/GAinQM.html