Orley C. Ashenfelter, D. C. (1999). Handbook of Labor Economics. ELSEVIER.
Lua i Stíl Chicago (17ú heag.)Orley C. Ashenfelter, David Card. Handbook of Labor Economics. ELSEVIER, 1999.
Lua MLA (8ú heag.)Orley C. Ashenfelter, David Card. Handbook of Labor Economics. ELSEVIER, 1999.
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