BioStor
 | Expedition to the Baltic provinces of Russia and Scandinavia Twenhofel W H Raymond P. E. (1916) Bulletin of The Museum of Comparative Zoology 56: 179-286 |
 | Trilobites of the Ordovician Table Head formation, western Newfoundland H B Whittington (1965) Bulletin of The Museum of Comparative Zoology 132: 275-441 |