A.  Pekkarinen and Teräs, I., ?Suomen kimalaisista ja loiskimalaisista (On Finnish bumblebees and cuckoo bumblebees (Apidae))?, Luonnon Tutkija, vol. 81, pp. 1-24, 1977.

A.  Pekkarinen, Teräs, I., Viramo, J., and Paatela, J., ?Distribution of bumble­bees (Hymenoptera, Apidae: Bombus and Psithyrus) in Eastern Fennoscandia.?, Notulae Entomologicae, vol. 61, pp. 71-89, 1981.