@article { santos21,
	journal = {Philosophical Transactions of the Royal Society B},
	keywords = {Multi-Agent Societies;Game Theory;},
	number = {20200291},
	pages = {(Accepted)},
	publisher = {Royal Society},
	title = {The complexity of human cooperation under indirect reciprocity},
	volume = {376},
	year = {2021},
	author = {Fernando P. Santos and Jorge M. Pacheco and Francisco C. Santos}
}