Relativity and gravitation in general: proceedings of the Spanish Relativity Meeting in honour of the 65th birthday of Lluís Bel. Salamanca, Spain, 22-25 September 1998

coord. por Jesús Martín Martín, Eduardo Ruiz Carrero, Fernando Atrio Barandela, Alfred Molina i Compte; Lluís Bel (hom.)

World Scientific, 1999. ISBN 9810239327