@article {1092,
	title = { Evolution and genetics of Bombus and Psithyrus species (Hymenoptera, Apidae)},
	journal = {Zool. Scripta},
	volume = {8},
	year = {1979},
	pages = {316-317},
	author = {Pekkarinen, A.}
}
@article {1088,
	title = {Adaptation of  the mouthparts in bumblebees},
	journal = {Zool. Scripta},
	volume = {5},
	year = {1976},
	pages = {189},
	author = {Pekkarinen, A.}
}
