@book{13293,
	author = {Conference on "Nonlinear Differential Equations", Trento, Italy, May 25-30, 1980 and Mottoni, Piero de ; ed.},
	title = {Nonlinear differential equations; invariance, stability and bifurcation; proceedings of an international conference},
	publisher = {Academic Press},
	year = {1981},
	address = {New York}
}