Kerr-Schild Rides Again
General Relativity and Gravitation
It is shown that the necessary and sufficient condition that an algebraically special vacuum solution be of the (generalized) Kerr-Schild form is that it have a preferred Killing vector. The transformation is applied to a known type-III solution to obtain a type-II vacuum solution of Einstein's equations.
Kerr-Schild rides again, M.E.Fels, A. Held, General Relativity and Grav- itation, 21(1), 1989, 61-68.