Original: T. K. Velu Pillai, (1940) "The Travancore State Manual"; 4 volumes; Trivandrum Caldwell, R (1998) "A comparative grammar of the Dravidian or South-Indian family of languages" 3rd ed.
Simplified: Robert Caldwell., "A comparative grammar of the Dravidian or South-Indian family of languages" 3rd ed.