@book{8700,
	author = {Buchi, J. Richard and Siefkes, Dirk and Siefkes, Dirk ; jt. auth.},
	title = {The monadic second order theory of countable ordinals},
	publisher = {Springer-Verlag},
	year = {1973},
	series = {Lecture notes in Mathematics},
	address = {Berlin},
	note = {"Decidable theories-II"}
}