9th Italian Conference on General Relativity and Gravitational Physics, Capri (Napoli) September 25-28, 1990Italian Conference on General Relativity and Gravitational Physics (9th 1990 Capri, Italy), Italy) Italian Conference on General Relativity and Gravitational Physics (9th : 1990 : Capri, R. De Ritis, R. Cianci, G. Marmo, C. Rubano, P. Scudellaro · First published 1990Open the Tome