@book{5016,
	author = {Kovacic, Ivana and Brennan, Michael J.},
	title = {The Duffing Equation :},
	publisher = {John Wiley & Sons,},
	year = {c 2011.},
	address = {West Sussex, United Kingdom :},
	url = {https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/9780470977859?download=true}
}