1. E. T. Newman and R. Penrose, J. Math. Phys. 3, 566 (1962).
2. S. Chandrasekhar, The Mathematical Theory of Black Holes (Clarendon Press, Oxford, Oxford University Press, 1983).
3. E. J. Flaherty, Hermitian and Kahlerian Geometry in Relativity, (Lecture notes in Physics 46, Springer Verlag, Berlin, New York, 1976).
4. H. Stephani, D. Kramer, M. A. H. MacCallum, C. Hoenselaers, and E. Herlt, Exact Solutions of Einstein Field Equations (2nd Ed., Cambridge University Press, 2002).
5. S. Jogia and J. B. Griffiths, Gen. Rel. Grav. 12 (8), 597 (1980).