1. T. Kaluza, Zum Unitätsproblem der Physik, Sitzungsber. Preuss. Akad. Wiss. Berlin (Math. Phys.) 1921 (1921) 966 [arXiv:1803.08616] [INSPIRE].
2. O. Klein, Quantum Theory and Five-Dimensional Theory of Relativity. (In German and English), Z. Phys. 37 (1926) 895 [INSPIRE].
3. T. Appelquist, A. Chodos and P.G.O. Freund, Modern Kaluza-Klein theories, Addison-Wesley Publishing Company (1987) [ISBN: 9780201098297] [INSPIRE].
4. N. Straumann, On Pauli’s invention of nonAbelian Kaluza-Klein theory in 1953, in the proceedings of the 9th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Gravitation and Relativistic Field Theories (MG 9), Rome Italy, July 2–9 (2000) p. 1063–1066 [gr-qc/0012054] [INSPIRE].
5. T. Eguchi, P.B. Gilkey and A.J. Hanson, Gravitation, Gauge Theories and Differential Geometry, Phys. Rept. 66 (1980) 213 [INSPIRE].