@inproceedings{allen1998fir,
  title={The Fir Tree Field shaft: the date and archaeological and palaeoenvironmental potential of a chalk swallowhole feature},
  author={ALLEN, MICHAEL J and GREEN, MARTIN},
  booktitle={Proceedings of the Dorset Natural History and Archaeological Society},
  volume={120},
  pages={25--38},
  year={1998}
}