@book {47,
	title = {The Lichen Flora of Great Britian and Ireland},
	year = {1992},
	publisher = {Natural History Museum Publications},
	organization = {Natural History Museum Publications},
	address = {London},
	author = {O.W. Purvis and D.M. Moore and B.J. Coppins and D.L. Hawksworth and P.W. James}
}
@book {1453,
	title = {Lichens},
	series = {The new naturalist},
	year = {2000},
	pages = {288},
	publisher = {HarperCollins},
	organization = {HarperCollins},
	address = {London},
	isbn = {0002200821},
	author = {Oliver Gilbert}
}
@book {53,
	title = {Lichens of North America},
	year = {2001},
	publisher = {Yale University Press},
	organization = {Yale University Press},
	issn = {0300082495},
	author = {Brodo, Irwin M and Sylvia Duran Sharnoff and Susan Laurie-Bourque and Stephen Sharnoff}
}
