Hong, Yong, and Samuel W. James. 2009. “New Earthworms of the Pheretima Urceolata Species Group (Oligochaeta: Megascolecidae) from Southern Luzon, Philippines”. Zootaxa 2059 (1). Auckland, New Zealand:33–45. https://doi.org/10.11646/zootaxa.2059.1.3.