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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.
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Hodson |
1957 |
Marker horizons in the Namurian of Britain, Ireland, Belgium and Western Germany.
Association pour l'Etude de Paléontologie et de la Stratigraphie Houillères, Publication 24: 1-26, fig.1-3, pl.1-7; Bruxelles.
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