Engel, Michael S., and Denis Michez. “A New Vernal Species of Hesperapis from the Lower Midwestern United States (Hymenoptera: Melittidae)”. Journal of Melittology, no. 98 (December 4, 2020): 1–11. Accessed March 14, 2025. https://journals.ku.edu/melittology/article/view/14816.