Cita APA (7th ed.)

Asimov, I. (2016). Foundation and empire (NA.). Harper Voyager.

Cita Chicago (17th ed.)

Asimov, Isaac. Foundation and Empire. NA. London: Harper Voyager, 2016.

Cita MLA (9th ed.)

Asimov, Isaac. Foundation and Empire. NA. Harper Voyager, 2016.