	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	1895	Cephalopoda. In: G.J.Hinde & H.Fox: On a Well-marked Horizon of Radiolarian Rocks in the Lower Culm Measures of Devon, Cornwall and West Summerset. Quarterly Journal of the Geological Society of London, 51: 652-653, London.