@book{16431,
	author = {Leon, Manuel De and Rodrigues, Paulo R.},
	title = {Generalized classical mechanics and field theory; a geometrical approach of Lagrangian and Hemiltonian formalisms involving higher order derivatives},
	publisher = {North-Holland,},
	year = {1985},
	series = {North-Holland Mathematics studies },
	address = {Amsterdam:}
}