Chang, C.-H., Snyder, B.A. & Szlavecz, K. (2016)

Asian pheretimoid earthworms in North America north of Mexico: An illustrated key to the genera Amynthas, Metaphire, Pithemera, and Polypheretima (Clitellata: Megascolecidae)

. Zootaxa, 4179 (3), 495–529.