Cita APA (7th ed.)

Malthus, T. R. (1970). An essay on the principle of population. Penguin Books.

Cita Chicago (17th ed.)

Malthus, T. R. An Essay on the Principle of Population. Harmondsworth: Penguin Books, 1970.

Cita MLA (9th ed.)

Malthus, T. R. An Essay on the Principle of Population. Penguin Books, 1970.