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Type	Originator	Title	Date
	Davies,I	History of Coal Mining in the Amman Valley	2017
	Jeffreys,A (ed)	Mines in Scotland	2008
	Spargo,T	Mines of Wales
	Lewis,M.J.T & Denton,J.H	Rhoysdd Slate Quarry	2018
	Geografiska Annaler	Some Remarks on Swedish Speleology	1965
	Lloyd,O.C	The Hepste River Caves	1979
	Middleton,J & Waltham,A	The Underground Atlas	1992