00308nam a2200109 a 450000500170000002000150001708200170003210000250004924500580007426000460013230000200017820251203091619.0  a0674506758  a331.12,bfre  aFreeman, Richard B.R  aLabor markets in action:essays in empirical economics  aCambridge: Harvard University Pressc1989  axii,354p.c23cm