Census of India, 1981 <br/><br/>
General economic tables. Kerala. V. 10, Pt. 3 A & B (ii) 

 - Kerala  Govt. Press           1981 
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Dewey Class. No.: </label>Y:5.212sN81, M1.10-3A&B(ii)