Pekkarinen, A., and L. Huldén. “Distribution and Phenology of the <i>Ancistrocerus</i> and <i>Symmorphus</i> Species in Eastern Fennoscandia (Hymenoptera, Eumenidae)¹”. Entomologica Fennica, vol. 2, no. 3, Sept. 1991, pp. 179-8, doi:10.33338/ef.83547.