	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.
	Crick	1911	Notes on Carboniferous Cephalopoda from the Neighbourhood of Exeter. Quarterly Journal of the Geological Society of London, 1911: 399-414, pl.32; London.