@book{21172,
	author = {Pugh, Philip },
	title = {Observing the Messier Objects with a Small Telescope},
	publisher = {Springer New York},
	year = {2012},
	series = {The Patrick Moore Practical Astronomy Series},
	address = {New York},
	url = {http://doi.org/10.1007/978-0-387-85357-4}
}