Bumblebees of wisconsin
Medler, J.T., Carney, D.W.
Bumblebees of wisconsin - Madison 1963 - 1-47 p. - Wisconsin Agriculture Experiment Station. Research Bulletin No. 240 .
Bumblebees of wisconsin - Madison 1963 - 1-47 p. - Wisconsin Agriculture Experiment Station. Research Bulletin No. 240 .