Columbia subject headings:
Commerce--Mathematical models.
Foreign exchange--Mathematical models.
Non-tariff trade barriers--Mathematical models.
Tariff--Mathematical models.
Harvard subject headings:
Commerce--Mathematical models
Foreign exchange--Mathematical models
Non-tariff trade barriers--Mathematical models.
Tariff--Mathematical models.
Princeton subject headings:
Commerce--Mathematical models.
Foreign exchange--Mathematical models.
Non-tariff trade barriers--Mathematical models.
Tariff--Mathematical models.