Times Of India (India). 15 April 2010 [2012-08-21]. (原始内容存档于2018-12-25). Railway Unit. Official webpage of Indian Railways. [6 June 2009]. (原始内容存档于2018-12-25)
Press Trust of India. Hindi, not a national language: Court. The Hindu. Ahmedabad. 2010-01-25 [2014-12-23]. (原始内容存档于2014-07-04). Ministry of Home Affairs