Heater, 2006, p. 34. Heater, Derek Benjamin (2006). Citizenship in Britain: a history. Edinburgh University Press. pp. 33,34. ISBN0-7486-2226-8.
Heater, 2006, p. 34 cites Andrew Sharp 1983, p. 177 Heater, Derek Benjamin (2006). Citizenship in Britain: a history. Edinburgh University Press. pp. 33,34. ISBN0-7486-2226-8.
Harrison y Boyd, 2003, p. 197. Harrison, Kevin; Boyd, Tony (2003). Understanding political ideas and movements: a guide for A2 politics students (illustrated ediciĆ³n). Manchester University Press. pp. 197. ISBN0-7190-6151-2.