Shepherd, Marc. "Introduction: Historical Context", The Grand Duke, p. vii, New York: Oakapple Press, 2009. Linked at "The Grand Duke", Archived 20 June 2009 at the Wayback MachineThe Gilbert and Sullivan Archive, retrieved 7 July 2009.
Crowther, Andrew. "The Carpet Quarrel Explained", The Gilbert and Sullivan Archive, 13 August 2018, retrieved 10 October 2021
Stedman (p. 95): In "a Gilbertian invasion" plot, outsiders change a given society, as where the Thespians take control of Olympus in Thespis. Similarly, in The Wicked World, Broken Hearts, Princess Ida and several of Gilbert's other works, men introduce the element of mortal love into a previously content female society. See Introduction to Broken Hearts[dead link] at The Gilbert and Sullivan Archive, retrieved 11 March 2009
Shepherd, Marc. "Introduction: Historical Context", The Grand Duke, p. vii, New York: Oakapple Press, 2009. Linked at "The Grand Duke", Archived 20 June 2009 at the Wayback MachineThe Gilbert and Sullivan Archive, retrieved 7 July 2009.