1. Why Countertrade?;Cooper;Across the Board,1984
2. Ranges For Negotiating Countertrade Transactions Under the Comparative Advantage Theory;Fuh,1987
3. Convergence of Expert Concensus Through Feedback;Helmer,1964
4. Analysis of the Future: The Delphi Method;Helmer,1966
5. The Delphi Method;Linston,1975