@article { santos16,
	journal = {PLoS Computational Biology},
	keywords = {Multi-Agent Societies;Game Theory;Miscellaneous;},
	number = {1},
	pages = {e1004709},
	title = {Social norms of cooperation in small-scale societies},
	volume = {2},
	year = {2016},
	author = {Fernando P. Santos and Francisco C. Santos and Jorge M. Pacheco}
}