1. A review of geochemical data related to the Northwest European gas province;Barnard,1983
2. Bradburn, E., 1980. Private communication.
3. Petrographic texture and vitrinite reflectance variation on the Alston Block;Creany,1980
4. A study of variation in gas content of coal seams in relation to petrographic and stratigraphic variations;Creedy;M.Sc. Thesis, University College, Cardiff,1979