|[http://www.textbooksonline.tn.nic.in/Books/Std08/Std08-III-MSSS-TeM-2.pdf Tamilnadu Textbook Class - IX - Chapter - 13 - Conservation of plants and animals Page No 118-133]
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|[http://www.textbooksonline.tn.nic.in/Books/Std08/Std08-III-MSSS-TeM-2.pdf Tamilnadu Textbook Class - VIII - Chapter - 13 - Conservation of plants and animals Page No 118-133]