@book{10440,
	author = {Courvoisier, T. J. L., ed.},
	title = {Active galactic nuclei},
	publisher = {Springer-Verlag},
	year = {1990},
	series = {SAAS-FEE Advanced Course 20 Lecture Notes 1990 Swiss Society for Astrophysics and Astronomy},
	address = {Berlin}
}