@article { vukov11,
	journal = {Journal of Theoretical Biology },
	keywords = {Game Theory;Multi-Agent Societies;},
	pages = {37-41},
	title = {Escaping the tragedy of the commons via directed investments},
	volume = {287},
	year = {2011},
	author = {Jeromos Vukov and Francisco C. Santos and Jorge M. Pacheco}
}