@article{Pagel1994,
	Author = {Mark Pagel},
	Journal = {Proceedings of the Royal Society of London, Series B: Biological Sciences},
	Title = {Detecting Correlated Evolution on Phylogenies: A General Method for the Comparative Analysis of Discrete Characters},
	Pages ={37-45},
	Volume = {255},
	Number = {1342},
	Year = {1994}}