Wolfgang Stolper, 89; Economist Specialized in International Trade

Wolfgang F. Stolper, 89, an economist whose work included a theory used to explain the effect of international trade on wages, died Monday in Ann Arbor, Mich., during surgery to clear a blood clot.

Stolper was perhaps best known for the 1941 Stolper-Samuelson theorem, done in collaboration with Paul Samuelson, which changed existing notions about the effect of open trade on the economies of trading nations.

Stolper’s contribution said that while trade stimulates economic growth, it’s not always beneficial to all workers.

Born in Vienna, Stolper’s family moved to Berlin after World War I but later fled the rise of Nazism in Germany.

Stolper attended Harvard, where he received his master’s degree and doctorate in economics. He also taught at Harvard, as well as at Radcliffe and Swarthmore, before joining the University of Michigan, where he was a professor from 1949-82.