1. Archer , A. A. 1968 The Upper Carboniferous and later formations of the Gwendraeth Valley and adjoining areas. Geology of the South Wales Coalfield, Special Memoir Mem. geol. Surv. U.K.
2. The Old Red Sandstone of Brown Clee Hill and the adjacent area;Ball;Bull. Br. Mus. nat. Hist.,1961
3. Cardy , W. F. G. 1967 Final report on the geology of the Lower Swansea Valley Project Area Lower Swansea Valley Project