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PP- 155-210, pis. 5-9 and 20 figs. 

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 Handlirsch, A. 



'88a Uber die Variabilitat und die geographlsche'^Verbreitung der Hummeln. 



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 Huber, P. 



'02 Observations on Several Species of the Genus Apis, known by the name of 



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'22 a Notes on Psithyrus, with Records of Two New American Hosts. BIOL. 



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 '23 a Breeding Experiments with Confined Bremus (Bombus) Queens. BIOL. 



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