Gstöhl, Sieglinde«The European Union's Trade Policy»(PDF)(en anglès).Ritsumeikan International Affairs.Institute of International Relations and Area Studies, Ritsumeikan University,vol. 11,2013,p.1–22. Arxivat de l'original el 2016-05-27.
Tindal, David Ernest.«Chapter Two: Trade Tariffs, Export Restrictions and Boycotts». A: Economic Statecraft in the Ancient Greek World(tesi)(en anglès). University of New England,2023-07-12,p.41-78.
Gstöhl, Sieglinde«The European Union's Trade Policy»(PDF)(en anglès).Ritsumeikan International Affairs.Institute of International Relations and Area Studies, Ritsumeikan University,vol. 11,2013,p.1–22. Arxivat de l'original el 2016-05-27.