@book {7367,
	title = {Evolving hierarchical systems: their structure and representation},
	year = {1985},
	pages = {343},
	publisher = {Columbia University Press},
	organization = {Columbia University Press},
	address = {New York},
	keywords = {biology, evolution, evolutionary theory, hierarchy, network, philosophy},
	isbn = {0-231-06016-5},
	author = {Salthe, Stanley N.}
}
@article {6074,
	title = {Biological diversification and its causes},
	journal = {Annals of the Missouri Botanical Garden},
	volume = {72},
	year = {1985},
	pages = {794-822},
	keywords = {ecology, evolution, evolutionary theory, macroevolution, phylogeny},
	author = {Cracraft, Joel}
}
