@article {VanDerWal2009EM,
	title = {{Selecting pseudo-absence data for presence-only distribution modeling: How far should you stray from what you know?}},
	journal = {Ecological Modelling},
	volume = {220},
	year = {2009},
	pages = {589{\textendash}594},
	author = {VanDerWal, J. and Shooa, L.~P. and Grahamb, C. and Williams, S.~E.}
}