https://www.mofa.go.jp/files/100114853.pdf
https://www.eia.gov/energyexplained/us-energy-facts/imports-and-exports.php
http://www.morganstanley.com/ideas/global-trade-protectionism
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/899991/200713_BPDG_-_Border_Operating_Model_FINAL_1320_edit.pdf