Cita APA (7th ed.)

Mulligan, C. B., & Sala-i-Martin, X. (1999). Social security in theory and practice (II): Facts and political theories. National Bureau of Economic Research.

Cita Chicago (17th ed.)

Mulligan, Casey B., i Xavier Sala-i-Martin. Social Security in Theory and Practice (II): Facts and Political Theories. Cambridge: National Bureau of Economic Research, 1999.

Cita MLA (9th ed.)

Mulligan, Casey B., i Xavier Sala-i-Martin. Social Security in Theory and Practice (II): Facts and Political Theories. National Bureau of Economic Research, 1999.