1. R. Penrose, The Road to Reality: A Complete Guide to the Laws of the Universe (Jonathan Cape, London, 2004). Vintage IBN:9780-679-77631-4
2. J. Bjorken, S. Drell, Relativistic Quantum Mechanics (McGraw-Hill, 1964). ISBN:0-07-005493-2
3. R. Penrose, Structure of space-time, in Battelle Rencontres, 1967 Lectures in Mathematics and Physics, eds. by C.M. DeWitt, J.A. Wheeler (Benjamin, New York, 1968)
4. R. Penrose, W. Rindler, Spinors and Space-Time, Vol. 1: Two-Spinor Calculus and Relativistic Fields (Cambridge University Press, Cambridge, 1984)
5. W.T. Payne, Elementary spinor theory. Am. J. Phys. 20, 253–262 (1952)