You can do simple searches using this form:

Type	Originator	Title	Date
	De Block,G & Fontaine,J.P	Bibliographie Speleologique Belge 1907-1964	1968
	Merk,C	Excavations at The Kesslerloch	1876
	Farr,M	The Darkness Beckons	1991
	Brown,G. B	The art of the cave dweller	1932
	Thomas,A	The story of Priddy	1989
	Schabdach,H	Unterirdische Welten	2000