Baker, D. B. (2002). On Palaearctic and Oriental species of the genera Pseudapis W.F. Kirby, 1900, and Nomiapis Cockerell, 1919 (Hymenoptera, Halictidae, Nomiinae). Beiträge Zur Entomologie = Contributions to Entomology, 52(1), 1–83. https://doi.org/10.21248/contrib.entomol.52.1.1-83