@article {600551,
	title = {Quantitative Historical Analyses Uncover a Single Dimension of Complexity that Structures Global Variation in Human Social Organization},
	journal = {PNAS},
	year = {2017},
	url = {doi:10.1073/pnas.1708800115},
	author = {Peter Turchin and Peter K. Bol and et al.}
}
