Books on the Octonions:

1. John H. Conway and Derek A. Smith, On Quaternions and Octonions, A K Peters, Ltd., Boston, 2003.

2. Geoffrey M. Dixon, Division Algebras: Octonions, Quaternions, Complex Numbers and the Algebraic Design of Physics, Kluwer Academic Publishers, Boston, 1994.

3. Feza Gürsey and Chia-Hsiung Tze, On the Role of Division, Jordan, and Related Algebras in Particle Physics, World Scientific, Singapore, 1996.

4. S. Okubo, Introduction to Octonion and Other Non-Associative Algebras in Physics, Cambridge University Press, Cambridge, 1995.

   Other related books:

5. Clifford Algebras with Numeric and Symbolic Computations, eds. Rafa\l Ab\l amowicz, Pertti Lounesto, Josep M. Parra, Birkhäuser, Boston, 1996.

6. Stephen L. Adler, Quaternionic Quantum Mechanics and Quantum Fields, Oxford University Press, New York, 1995.

7. Emil Artin, Geometric Algebra, John Wiley & Sons, New York, 1957 & 1988.

8. William E. Baylis, Electrodynamics: a Modern Geometrical Approach, Birkhäuser Boston, Cambridge, 1999.

9. Michael J. Crowe, A History of Vector Analysis, Dover, Mineola, NY, 1984 (originally published 1967).

10. M. B. Green, J. H. Schwarz, and E. Witten, Superstring Theory, Cambridge University Press, Cambridge, 1987.

11. F. Reese Harvey, Spinors and Calibrations, Academic Press, Boston, 1990.

12. Nathan Jacobson, Structure and Representations of Jordan Algebras, Amer.  Math.  Soc. Colloq. Publ. 39, American Mathematical Society, Providence, 1968.

13. P. Lounesto, Clifford Algebras and Spinors, Cambridge University Press, Cambridge, 1997.

14. Roger Penrose and Wolfgang Rindler, Spinors and Space-Time, Cambridge University Press, Cambridge, 1984 & 1986.

15. Boris Rosenfeld, Geometry of Lie Groups, Kluwer, Dordrecht, 1997.

16. Richard D. Schafer, An Introduction to Nonassociative Algebras, Academic Press, New York, 1966 & Dover, Mineola NY, 1995.