Vallejo Zamudio, L. E. (2015). The fall in oil prices and its impact on the Colombian economy. Universidad Pedagógica y Tecnológica de Colombia.
Čikaški stil citiranja (17. izdanje)Vallejo Zamudio, Luis E. The Fall in Oil Prices and Its Impact on the Colombian Economy. Universidad Pedagógica y Tecnológica de Colombia, 2015.
MLA način citiranja (9. izdanje)Vallejo Zamudio, Luis E. The Fall in Oil Prices and Its Impact on the Colombian Economy. Universidad Pedagógica y Tecnológica de Colombia, 2015.
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