@book{13581,
	author = {Godbillon, C. and Helfenstein, H. G. ; tr.},
	title = {Dynamical systems on surfaces},
	publisher = {Springer-Verlag},
	year = {1983},
	series = {Universitext},
	address = {Berlin},
	note = {"Tr. from the French by H. G. Helfenstein".}
}