Gravitational lenses : proceedings of a conference held in Hamburg, Germany, 9-13 September 1991 / R. Kayser, T. Schramm, L. Nieser (eds.). (Lecture notes in physics)
Gravitational lenses : proceedings of a conference held in Hamburg, Germany, 9-13 September 1991 / R. Kayser, T. Schramm, L. Nieser (eds.).