OPEN University of Sri Lanka <br/><br/>
Course of study leading to the degree of bachelor of science level 5-PSU 3118-ph 

 - Nugegoda  The Open University of Sri Lanka  1989 
 - 89 p. 
<br/><br/><label>ISBN: </label>123693 
<br/><br/><label>Dewey Class. No.: </label>541.345  / OPE