@book{16,
	author = {Ince, E. L.},
	title = {Integration of ordinary differential equations /},
	publisher = {Oliver and Boyd,},
	year = {1956 [reprinted 1967].},
	series = {[University mathematical texts. General editors: A.C. Altken ... D.E. Rutherford]},
	address = {Edinburgh ;},
	edition = {7th ed.}
}