OPEN University of Sri Lanka <br/><br/>
Course of study leading to the degree of bachelor of science-level 5 PSU 3121: n 

 - Nugegoda  The Open University of Sri Lanka  1991 
 - 45 p. 
<br/><br/><label>ISBN: </label>139442 
<br/><br/><label>Dewey Class. No.: </label>547.72  / OPE