@article {4154,
	title = {Another way of looking at the species problem: a reply to de Queiroz and Donaghue},
	journal = {Cladistics},
	volume = {6},
	year = {1990},
	pages = {77-81},
	keywords = {CLADISTICS, species, SPECIES CONCEPTS},
	author = {Wheeler, Q. D. and Nixon, Kevin C.}
}
@article {3204,
	title = {On Outgroups},
	journal = {Cladistics},
	volume = {9},
	year = {1993},
	pages = {413-426},
	keywords = {CLADISTICS, OUTGROUPS},
	author = {Nixon, Kevin C. and Carpenter, J. C.}
}
@article {3205,
	title = {On concensus, collapsibility, and clade concordance},
	journal = {Cladistics},
	volume = {12},
	year = {1996},
	pages = {305-321},
	keywords = {Clade, CLADISTICS},
	author = {Nixon, Kevin C. and Carpenter, James M.}
}
@article {3208,
	title = {An amplification of the phylogenetic species concept},
	journal = {Cladistics},
	volume = {6},
	year = {1990},
	note = {An excellent and concise account of the PSC; ; ;,},
	pages = {211-223},
	keywords = {CLADISTICS, PHYLOGENETIC SPECIES CONCEPT, species},
	author = {Nixon, Kevin C. and Wheeler, Q. D.}
}
