Ingram, G. K., & Liu, Z. (1998). Vehicles, roads, and road use: Alternative empirical specifications. World Bank.
Chicago Style (17. basım) AtıfIngram, Gregory K., ve Zhi Liu. Vehicles, Roads, and Road Use: Alternative Empirical Specifications. Washington, D.C: World Bank, 1998.
MLA (9th ed.) AtıfIngram, Gregory K., ve Zhi Liu. Vehicles, Roads, and Road Use: Alternative Empirical Specifications. World Bank, 1998.
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