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