[1] Einstein, A. (1905). On the Electrodynamics of Moving Bodies. Annalen der Physik , 17(10), 891-921.

[2] Hawking, S., & Penrose, R. (1970). The Singularities of Gravitational Collapse. Proceedings of the Royal Society A , 314(1519), 529-548. https://doi.org/10.1098/rspa.1970.0021

[3] Penrose, R. (2004). The Road to Reality . Jonathan Cape.

[4] Dirac, P.A.M. (1930). The Principles of Quantum Mechanics . Oxford University Press.