''Ohlin's reputation was only firmly secured by the publication of Interregional and International Trade, a book which won him the Nobel Prize. Starting from an article written in 1919 by his old teacher, Eli Heckscher, Ohlin developed the thesis that both interregional and international trade are devices for the spatial exchange of the goods and services produced by factors of production since these factors themselves are to a greater or lesser extent incapable of being moved in space -- think of land as the classic case of an immovable factor -- in consequence of which relative prices in different geographical locations depend on the relative scarcity of factor endowments in these locations. This 'Heckscher-Ohlin Theorem', as it was soon to be called, entered almost immediately into the textbook literature, although not without a push from Samuelson in the 1940s, and the stimulus of Leontief's apparent empirical refutation of the theorem in the 1950s. It is doubtful, however, whether any later textbook treatment improved on Ohlin's own masterful presentation . . . By the end of the book, the entire range of international economic problems has been discussed and, moreover, the intimate connections between location theory, regional economics, and international trade have been brilliantly displayed.'' (Mark Blaug, Great Economists Since Keynes, pp. 185-6)