N. Sasa et J. Satsuma, A SERIES OF EXACT-SOLUTIONS BASED ON A BILINEAR FORM OF THE STATIONARY AXIALLY SYMMETRICAL VACUUM EINSTEIN EQUATIONS, Journal of the Physical Society of Japan, 62(4), 1993, pp. 1153-1158
A series of exact solutions of the stationary axially symmetric vacuum
Einstein equations are discussed based on Hirota's bilinear method. T
he solutions are expressed in terms of some determinants and include N
eugebauer's soliton solutions as a particular case.