@inbook {1074,
	title = {Phylogenetic relatonships and the origin of social parasitism in Vespidae and and in Bombus and Psithyrus as revealed by enzyme genes},
	booktitle = { Teoksessa:  Howse, P.E. \& Clement, J.-L. (toim.), Biosystematics of social insects. Systematics Assoc. Spec. 19: 37-48.},
	year = {1981},
	author = {Pamilo, P. and Pekkarinen, A. and Varvio-Aho, S.-L.}
}
