World Register of Marine Species (WoRMS)
MolluscaBase eds. (2026). MolluscaBase. Orthoceras rectum Worthen, 1875&nbsp;&#8224;. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1884332 on 2026-08-29
Worthen, A. H. & Meek, F. B. (1875). Palaeontology of Illinois, Section 2, Descriptions of invertebrates. Geological Survey of Illinois. 6: 489–532, pls 23–33.