@article {Wolleben1977,
	title = {Paleontology of the Difunta group (Upper Cretaceous-Tertiary) in northern Mexico},
	journal = {Journal of Paleontology},
	volume = {51},
	number = {2},
	year = {1977},
	pages = {373{\textendash}398, pl. 1{\textendash}3},
	keywords = {RCBS, TIP},
	url = {http://www.jstor.org/stable/1303616},
	author = {Wolleben, J A}
}
