@book{320,
	author = {Vega, H.J. de and Sanchez, N},
	title = {Field theory,quantum gravity and strings: proceedings of a seminar series held at Daphe,Observatorie de},
	publisher = {Springer-Verlag},
	year = {1986},
	series = {Lecture notes in physics},
	address = {New York}
}