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.
Atenció: Aquestes cites poden no estar 100% correctes.