	Authors	Year	Title
	Butcher & Hodson	1960	A Review of the Carboniferous Goniatite Zones in Devon and Cornwall. Palaeontology, 3 (1): 75-81, pl.17-19; London.
	Phillips	1841	Figures and descriptions of the Palaeozoic fossils of Cornwall, Devon, and West Somerset. I-XII, 1-231, pl.1-60; London.