(South African Revenue Service) 美國 U.S. import codes (Harmonized Tariff Schedule)(页面存档备份,存于互联网档案馆) by U.S. International Trade Commission U.S. export codes(页面存档备份,存于互联网档案馆)
[2017-01-23]. (原始内容存档于2018-07-26). Export Partners of Togo. CIA World Factbook. 2015 [26 July 2016]. (原始内容存档于June 13, 2007). Import Partners of Togo. CIA World
Doing Business in Central African Republic 2012. World Bank. [2011-11-18]. (原始内容存档于2018-09-04). Export Partners of Central African Republic. CIA World Factbook
World Bank. [22 January 2014]. (原始内容存档于2016-08-12). Export Partners of Sudan. CIA World Factbook. 2012 [2013-07-27]. (原始内容存档于2018-07-27). Import Partners