Drinkwater, J. (1921). Oliver Cromwell: A play. Sidgwick & Jackson.
Lua i Stíl Chicago (17ú heag.)Drinkwater, John. Oliver Cromwell: A Play. London: Sidgwick & Jackson, 1921.
Lua MLA (8ú heag.)Drinkwater, John. Oliver Cromwell: A Play. Sidgwick & Jackson, 1921.
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