OPEN Univeristy of Sri Lanka <br/><br/>
Course of study leading to the degree of bachelor of science level 4 PSU 2115- p 

 - Nugegoda  Open University of Sri Lanka  1987 
 - 74 p. 
<br/><br/><label>ISBN: </label>123675 
<br/><br/><label>Dewey Class. No.: </label>541  / OPE