APA (7th ed.) Citation

Malthus, T. R. (2003). An Essay on the Principle of Population. Project Gutenberg.

Chicago Style (17th ed.) Citation

Malthus, T. R. An Essay on the Principle of Population. Project Gutenberg, 2003.

MLA (9th ed.) Citation

Malthus, T. R. An Essay on the Principle of Population. Project Gutenberg, 2003.

Warning: These citations may not always be 100% accurate.