Jackson, Donald Dale <br/><br/>
Underground worlds 
 Planet earth : underground worlds 

 - Alexandria, Va. :  Time-Life Books,  1982 
 - 176 
<br/><br/><label>Subjects--Topical Terms: </label><br/>CAVING--HISTORY--19TH CENTURY<br/>CAVING--HISTORY--20TH CENTURY<br/>CAVES
<br/><br/><label>LC Class. No.: </label>GV200.62  / J324U