John Ruskin (1868). “Time and Tide, by Weare and Tyne. Twenty-five letters to a Working Man of Sunderland (Thomas Dixon) on the laws of work ... Second edition”, p.37
Jean Drèze, Amartya Sen, World Institute for Development Economics Research (1997). “Indian Development: Selected Regional Perspectives”, p.5, Oxford University Press
"An Interview with the king of golf before the 38th Arnold Palmer Invitational". Golf Content Network Interview, golfcontentnetwork.com. March 16, 2016.