	Authors	Year	Title
	Calver & Ramsbottom	1961	Stratigraphical Palaeontology. In: J.R. Earp et al.: Geology of the Country around Clitheroe an Nelson. Memoir of the Geological Survey of Great Britain, Expl. one-inch Geol. Sheet 68, New Series: 174-207, pl.10,11; London.