Rickards, B. (1970). The Llandovery (Silurian) graptolites of the Howgill Fells, Northern England. Palaeontographical Society.
MLA CitationRickards, Barrie. The Llandovery (Silurian) Graptolites of the Howgill Fells, Northern England. Palaeontographical Society, 1970.
Warning: These citations have been automatically generated and may not always be 100% accurate..