1. 1949. The Middle Silurian Rocks of North Wales. London.
2. 1983. The geology of an area between Bala and Betwys-y-Coed, North Wales. Ph. D. Thesis. University of Cambridge, unpublished.
3. The emplacement of geochemically distinct groups of rhyolites during the evolution of the Lower Rhyolitic Tuff Formation caldera (Ordovician), North Wales, U.K.
4. 1992. The Llandovery Series. In: , and , (eds) Atlas of Palaeogeography and Lithofacies. Geological Society of London, Bath.
5. Canadian Soci;Clifton,1984