@book {727,
	title = {Lichen Flora of Great Britain and Ireland},
	year = {1992},
	pages = {710},
	publisher = {The Natural History Museum},
	organization = {The Natural History Museum},
	address = {London},
	author = {Purvis, O.W. and Coppins, B.J. and Hawksworth, D.L. and James, P. and Moore, D.M.}
}
@article {606,
	title = {Lichen Recolonization in London under Conditions of Rapidly Falling Sulfur-Dioxide Levels, and the Concept of Zone Skipping.},
	volume = {100},
	year = {1989},
	pages = {99-109},
	author = {Hawksworth, D.L. and McManus, P.M.}
}
@article {1607,
	title = {Lichen recolonization in London{\textquoteright}s cleaner air.},
	volume = {289},
	year = {1981},
	pages = {289-292},
	author = {Rose, C.I. and Hawksworth, D.L.}
}
@article {234,
	title = {Mapping studies},
	year = {1973},
	pages = {pp.38-76},
	institution = {Athlone press},
	address = {London},
	author = {Hawksworth, D.L.},
	editor = {Ferry, B. W. and Baddeley, M.S. and Hawksworth, D. L.}
}
@article {235,
	title = {Lichens as Pollution Monitors},
	year = {1970},
	institution = {Edward Arnold},
	address = {London},
	author = {Hawksworth, D.L. and Rose, F.}
}
@article {607,
	title = {Qualitave scale for estimating sulphur dioxoide in air pollution in England and Wales using epiphytic lichens},
	volume = {227},
	year = {1970},
	pages = {145-148},
	author = {Hawksworth, D.L. and Rose, F.}
}
