@article { pinheiro12,
	journal = {New Journal of Physics},
	keywords = {Game Theory;Multi-Agent Societies;Miscellaneous;},
	number = {073035},
	title = {How selection pressure changes the nature of social dilemmas in structured populations },
	volume = {14},
	year = {2012},
	author = {Flávio L. Pinheiro and Francisco C. Santos and Jorge M. Pacheco}
}