TY - BOOK TI - Working paper / National Bureau of Economic Research, Inc. T2 - NBER working paper series A2 - National Bureau of Economic Research CY - Cambridge, Mass. PB - National Bureau of Economic Research, Inc. PY - 1973 LA - English M3 - (DE-206)24 Arbeitspapier DE-206 M3 - (DE-206)34 Graue Literatur DE-206 M3 - Monografische Reihe (DE-588)4179998-7 (DE-627)104628669 (DE-576)209995106 gnd-content SN - 0898-2937 SN - 1058-8450 SN - 1073-2489 ER -