Cyfyngwch eich canlyniadau yn ôl:
- Pob un
- Coal mines and mining -- Great Britain., 3 canlyniadau
- Coal trade -- Great Britain., 2 canlyniadau
- Coal mines and mining -- Wales, South., 1 canlyniadau
- Coal trade -- Great Britain -- Records and correspondence, 1 canlyniadau
- Energy consumption -- Great Britain., 1 canlyniadau
- Political planning -- Great Britain., 1 canlyniadau
- Public utilities -- Great Britain., 1 canlyniadau
