Dunbar, R., & Botha, R. (2009). Why only humans have language. Oxford University Press.
Dyfyniad Arddull ChicagoDunbar, R., and R. Botha. Why Only Humans Have Language. Oxford University Press, 2009.
Dyfyniad MLADunbar, R., and R. Botha. Why Only Humans Have Language. Oxford University Press, 2009.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.