OPEN University of Sri Lanka <br/><br/>
Course of study leading to the degree of bachelor of science level 4 PSU 2113, I 

 - Nugegoda  Open University of Sri Lanka  1987 
 - 134 p. 
<br/><br/><label>ISBN: </label>103058 
<br/><br/><label>Dewey Class. No.: </label>546  / OPE