1. Coppock JD (1962) International Economic Instability. McGraw Hill, New York
2. Michaely M (1962) Concentration in International Trade. North-Holland, Amsterdam
3. Export Concentration and Fluctuations in Export Earnings: A Cross-Sectional Analysis;Missell BF;Am Econ Rev,1964
4. Kenen PB, Voivodas CS (1972) EXPORT INSTABILITY AND ECONOMIC GROWTH., 25(4), 791–804.
5. Glazakos C (1973) Export Instability and Economic Growth: A Statistical Verification, Economic Development and Cultural Change, 21: 670 – 78