Literature
- Baldock, D., Wood, T., Cross, I., Smit, J. 2018. The Bees of Portugal (Hymenoptera: Apoidea: Anthophila) – Entomofauna Suppl. S22: 1–164.
- Ban-Calefariu, C.M. and Sarospataki M. 2007. Contributions to the knowledge of Bombus and Psithyrus genera (Apoidea: Apidae) in Romania. Travaux du Museum NHN “Grigore Antipa” Vol. L pp. 239–258.
- Bieri, S. 2002. Die Bienen und Wespen des Fürstentums Liechtenstein. Amtlicher Lehrmittelverlag.
- Else, G.R. & Edwards, M. 2018. Handbook of the Bees of the British Isles. Ray Society, London.