Cita APA (7th ed.)

Helliwell, J. F. (1998). How much do national borders matter n. Brookings Institution Press.

Cita Chicago (17th ed.)

Helliwell, John F. How Much Do National Borders Matter N. Washington, D. C: Brookings Institution Press, 1998.

Cita MLA (9th ed.)

Helliwell, John F. How Much Do National Borders Matter N. Brookings Institution Press, 1998.