@article {34025,
	title = {Trilobite biofacies of the Cambrian-Ordovician boundary interval in northern North America},
	volume = {7},
	year = {1983},
	pages = {301-319},
	publisher = {Alcheringa : an Australasian Journal of Palaeontology},
	url = {http://pdfserve.informaworld.com/945896_770885140_795080891.pdf},
	author = {Ludvigsen, Rolf and Westrop, Stephen R.}
}
