Jackson, Donald Dale,  1935- <br/><br/>
Underground worlds / 
by Donald Dale Jackson and the editors of Time-Life Books. 
 - Alexandria, Va.:  Time-Life Books,  1982. 
 - 176 p. :  ill. (some col.) ;  29 cm 
 - Planet earth  6 .
<br/><br/>Includes index Bibliography: p. 170-172 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Caving--History--19th century<br/>Caving--History--20th century<br/>Caves