00257nam a2200121Ia 4500020001500000082001900015100001700034245002900051260002900080300001600109500000500125700000500130  a0155187813  a338.8bB635.EC  aBlair, J. M.  aEconomic concentrationb  aNew YorkbHarcourtc1972  axvii, 742p.  a  a