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Vănšno-ikonomičeski vrăzki na NRB
Menčeva, Liljana, (1988)
Economic co-operation between Nigeria and the socialist countries of Eastern Europe
Akinyemi, A. Bolaji, (1986)
Svetovnoto stopanstvo i dejstvieto na ikonomičeskite zakoni
Sergienko, Rajna, (1985)