@article {29507,
	title = {A multivariate analysis of the distribution of lichen on Populus tremuloides in west-central Canada},
	volume = {77},
	year = {1974},
	pages = {514-530},
	publisher = {The Bryologist},
	url = {http://www.plantbiology.siu.edu/faculty/vitt/pdf/33-1975.pdf},
	author = {Sherad, J. W. and Jonescu, M. E.}
}
