Williams, P. H., P. Dorji, Z. Ren, Z. Xie, and M. Orr. “Bumblebees of the Hypnorum-Complex World-Wide Including Two New Near-Cryptic Species (Hymenoptera: Apidae)”. European Journal of Taxonomy, vol. 847, no. 1, Nov. 2022, pp. 46–72, doi:10.5852/ejt.2022.847.1981.