http://keraladotpark.com/pdf/Archacological%20wonders.pdf A research paper from archaeologist Dr. P. Rajendran showing evidence of paleolithic age human inhabitation in Kerala. This includes the pictures of serpent idols made of clay and metal which belong to the mesolithic age.
WWW Virtual Library Sri Lanka. (2009). The original inhabitants of Lanka: Yakkas & Nagas. Available: http://www.lankalibrary.com/cul/yakkas.htm. Last accessed 7 March 2010.
