Ohlin developed a highly influential theory of international trade, the Hecksher-Ohlin model, along with his instructor, Eli Hecksher. The model, which ties in with David Ricardo's theory of comparative advantage, says that countries will export those goods that they can produce cheaply and import those goods that are expensive to produce. A country's relative advantages or disadvantages in land, labor and capital will determine what it makes most sense for the country to import and export. The Hecksher-Ohlin theory states that countries will specialize in industries where they can utilize their resources with the most efficiency.