1. Allen P. M. (1982) in Igneous Rocks of the British Isles, Lower Palaeozoic volcanic rocks of Wales, ed Sutherland D. S. (Wiley, London), pp 65–91.
2. Bryn Teg borehole;Allen;North Wales Bulletin Geological Survey of Great Britain,1978
3. Bailey R. J. (1969) in The Precambrian and Lower Palaeozoic Rocks of Wales, Ludlovian sedimentation in south central Wales, ed Wood A. (University of Wales Press, Cardiff), pp 283–304.
4. Rb-Sr whole-rock isochron evidence for the age of the Malvern Hills complex
5. Rb-Sr whole-rock isochron ages, δ18O values and geochemical data for the Sarn Igneous Complex and the Parwyd gneisses of the Mona Complex of Llŷn, N Wales