@book{180187,
	author = {McNamara, Geoff. and ebrary, Inc.},
	title = {Clocks in the sky},
	publisher = {Springer ;},
	year = {c2008.},
	series = {Springer-Praxis books in popular astronomy},
	address = {Berlin ;},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10294490}
}