personal link Diposkan oleh Govanus pada 2 Jun 2015 dalam English https://www.groundstability.com/public/web/home.jspx
OpenStreetMap
Discussion
Ulasan Govanus terhadap 2 Jun 2015 pada 19:28
https://www.gov.uk/coal-mining-records-data-deeds-and-documents#historic-data
Ulasan Govanus terhadap 2 Jun 2015 pada 19:29
https://www.gov.uk/government/publications/con29m-coal-and-brine-area-polygon-data
Ulasan Govanus terhadap 2 Jun 2015 pada 19:52
https://www.gov.uk/government/publications/ngec-regional-prime-maps