<ref name="Crozier_&_Pamilo_1996">{{cite book |first1=R. H. |last1=Crozier |first2=P. |last2=Pamilo |year=1996 |title=Evolution of social insect colonies. Sex allocation and kin selection |url= |location=Oxford |publisher=Oxford University Press |pages=viii + 306 pp. |isbn=}}</ref>