1. Chisolm, E.: Geometric Algebra. arXiv:1205.5935 . http://arxiv.org/abs/1205.5935
2. Doran, C., Lasenby, A.: Geometric Algebra for Physicists. Cambridge University Press, Cambridge (2007)
3. Doran, C., Lasenby, A., Gull, S.: States and operators in the spacetime algebra. Found. Phys. 23, 1239 (1993). http://www.mrao.cam.ac.uk/~clifford/publications/abstracts/states.html
4. Gull, S., Lasenby, A., Doran, C.: Imaginary Numbers are Not Real—The Geometric Algebra of Spacetime. Found. Phys. 23, 1175 (1993). http://www.mrao.cam.ac.uk/~clifford/publications/abstracts/imag_numbs.html
5. Hestenes, D.: New Foundations for Classical Mechanics: Fundamental Theories of Physics (Fundamental Theories of Physics). 2nd ed. Kluwer Academic Publishers, Berlin (1999)