Greathead, D. J., and N. L. Evenhuis. “Bombylioidea (Diptera: Bombyliidae; Mythicomyiidae) from the Island of Sokotra”. Zootaxa, vol. 14, no. 1, Nov. 2001, pp. 1–11, doi:10.11646/zotaxa.14.1.1.