Penney, David, et al. “Extraction of Inclusions from (sub)fossil Resins, With Description of a New Species of Stingless Bee (Hymenoptera: Apidae: Meliponini) in Quaternary Colombian Copal”. Paleontological Contributions, no. 7, May 2013, pp. 1-6, https://doi.org/10.17161/PC.1808.11103.