APA (7th ed.) Citation

Smith, A., & Skinner, A. (1999). The wealth of nations: Books 1-3. Penguin Books.

Chicago Style (17th ed.) Citation

Smith, Adam, and Andrew Skinner. The Wealth of Nations: Books 1-3. London: Penguin Books, 1999.

MLA (9th ed.) Citation

Smith, Adam, and Andrew Skinner. The Wealth of Nations: Books 1-3. Penguin Books, 1999.