00294nam a2200109Ia 4500082001700000100001800017245009000035260003500125300001400160500000500174700000500179  a382bO152.IT  aOlsen, Erling  aInternational trade theory and regional income differences; United States 1880-1950b  aAmsterdambNorth-Hollandc1971  axv, 221p.  a  a