Cyfyngwch eich canlyniadau yn ôl:
- Pob un
- Coal -- Transportation -- Wales, South., 1 canlyniadau
- Coal trade -- Prices -- Wales, South., 1 canlyniadau
- Coal shipping terminals., 1 canlyniadau
- Coal -- Transportation -- Great Britain., 1 canlyniadau
- Coal mines and mining -- Labor productivity., 1 canlyniadau
- Coal mines and mining -- Employees -- Wales., 1 canlyniadau