NOVIKOV-TYPE COORDINATES FOR HJ SEPARABLE METRICS Article Gupta S., Mitskíevič N. General Relativity and Gravitation. Vol. 15. 1983. P. 7-19
THE NUT METRIC IN SYNCHRONOUS COORDINATES Article Gupta S. Physics Letters, Section A: General, Atomic and Solid State Physics. Vol. 87. 1982. P. 220-222