Johnston, R. J. (1976). The world trade system: Some enquiries into its spatial structure. St. Martin's Press.
Lua i Stíl Chicago (17ú heag.)Johnston, Ronald John. The World Trade System: Some Enquiries into Its Spatial Structure. New York: St. Martin's Press, 1976.
Lua MLA (9ú heag.)Johnston, Ronald John. The World Trade System: Some Enquiries into Its Spatial Structure. St. Martin's Press, 1976.
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