Yj. Gao et Zz. Zhong, LINEAR DOUBLE UNIVERSAL GRASSMANN MANIFOLD METHOD FOR THE STATIONARY AXISYMMETRICAL VACUUM GRAVITATIONAL-FIELD EQUATIONS, International journal of theoretical physics, 35(2), 1996, pp. 277-286
Nagatomo's universal Grassmann manifold scheme is extended to a double
form, which is used to find the exact solutions of the stationary axi
symmetric vacuum gravitational field equations. Some new results are g
iven.