Williams, A. (1963). The Caradocian brachiopod fauna of the Bala District, Merionethshire. Bulletin of the British Museum (Natural History), Geology. 8: 327-471.
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Williams, A.
1963
The Caradocian brachiopod fauna of the Bala District, Merionethshire
Bulletin of the British Museum (Natural History), Geology