Cita APA (7a ed.)

Heckman, J. L. (1999). Causal parameters and policy analysis in economics: A twentieth century retrospective. National Bureau of Economic Research.

Cita Chicago Style (17a ed.)

Heckman, James L. Causal Parameters and Policy Analysis in Economics: A Twentieth Century Retrospective. Cambridge: National Bureau of Economic Research, 1999.

Cita MLA (9a ed.)

Heckman, James L. Causal Parameters and Policy Analysis in Economics: A Twentieth Century Retrospective. National Bureau of Economic Research, 1999.