United States 27
Greece 19
Great Britain 15
Ελλάδα 11
Developing countries 8
Europe 4
Soviet Union 4
Netherlands 3
Μεγάλη Βρετανία 3
European Union countries 2
Germany (West) 2
Japan 2
Mathematical models 2
Underdeveloped areas 2
Australia 1
Austrian 1
Central America 1
Chile 1
China 1
Epirus (Greece) 1
European Economic Community 1
European Economic Community countries 1
Germany, West 1
Hungary 1
India 1
Indian 1
Indonesia 1
Interlake Region (Man.) 1
Israel 1
Italy 1
Ivory Coast 1
Korea 1
Mexico 1
New England 1
North Sea 1
Philippines 1
Punjab (State) 1
Tariff 1
Yugoslavia 1
Ηνωμένες Πολιτείες 1
Κορέα 1
Υπανάπτυκτες χώρες 1
Χιλή 1