@book{208053,
	author = {Ralph, Jeff. and O'Neill, Rob.},
	title = {A practical introduction to index numbers /},
	publisher = {Wiley,},
	year = {2015.},
	address = {Chichester, West Sussex, UK :},
	url = {http://onlinelibrary.wiley.com/book/10.1002/9781118977781}
}