Obert, Leonard,  1906- <br/><br/>
Rock mechanics and the design of structures in rock 
Leonard Ober and Wilbur I. Duvall. 
 - New York :  Wiley,  1967 
 - 650 p. ;  23 cm. 
<br/><br/><label>ISBN: </label>0471652350 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Rock mechanics.<br/>Underground construction.