@book{509,
	author = {Sydsæter, Knut and Hammond, Peter},
	title = {Further mathematics for economic analysis},
	publisher = {Prentice Hall},
	year = {2008},
	address = {Harlow :},
	edition = {2a. ed.},
	url = {https://biblioeco.unsa.edu.ar/pmb/images/libros/Futher mathematics for economic analysis2-l118921.jpg}
}