BioStor
 | The genera of Rhamnaceae in the southeastern United States G K Brizicky (1964) Journal of the Arnold Arboretum 45: 439-463 |
 | The taxonomy and phylogeny of the genus Polyura Billberg (Lepidoptera: Nymphalidae) Robert L Smiles (1982) Bulletin of the British Museum (Natural History) Entomology 44(3): 115-237 |