Ponrajaha, A. J. P.  <br/><br/>
Tunnelling in rocks 

 - Engineering Geology Division  Colombo   1999 
 - 99p.  fig. 
<br/><br/><label>Nat. Bib. No.: </label>6869 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Engineering
<br/><br/><label>Universal Decimal Class. No.: </label>624.19  / PON