Census of India, 1961 <br/><br/>
General economic tables. ( tables B1 to B4). Kerala. V. 7, Part 2 B 1 

 - Kerala  Govt. Press           1961 
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Dewey Class. No.: </label>Y:5.212sN61, K1.7-2B1