Rohrlich, F (1993). "Potentials". In Parker, S.P. (ed.). McGraw Hill Encyclopaedia of Physics (2nd ed.). New York. p. 1072. ISBN0-07-051400-3.{{cite encyclopedia}}: CS1 maint: location missing publisher (link)
arxiv.org
Sean M. Carroll, "Lecture Notes on General Relativity" (arXiv:gr-qc/9712019), equations 6.20, 6.21, 6.22, 6.74
