T. K. Velu Pillai, -LRB- 1940 -RRB- '' The Travancore State Manual '' ; 4 volumes ; Trivandrum Caldwell, R -LRB- 1998 -RRB- '' A comparative grammar of the Dravidian or South-Indian family of languages '' 3rd ed.
Robert Caldwell / PERSON., '' A comparative grammar of the Dravidian or South-Indian family of languages '' 3rd ed.