Black Holes: Theory and Observation Proceedings of the 179th W.E. Heraeus Seminar Held at Bad Honnef, Germany, 18-22 August 1997 - Hehl, Friedrich W.; Hehl, Friedrich W.; Kiefer, Claus; Kiefer, Claus; Metzler, Ralph J.K; Metzler, Ralph J.K (Springer Berlin Heidelberg : Imprint: Springer, 1998)