1. Russian State Archive of Social and Political History (RGASPI), Moscow.
2. George Hardy, Those Stormy Years. Memoirs of the Fight for Freedom on Five Continents (London: Lawrence & Wishart, 1956).
3. Internationales Propaganda- und Aktionskommittee der revolutionären Transportarbeiter, Die 5. Internationale Konferenz der Revolutionären Transportarbeiter Abgehalten in Moskau im April 1928 (Moskau: Internationales Propaganda- und Aktionskommittee der revolutionären Transportarbeiter, 1928).
4. [ISH], The World Unity Congress of the International Water Transport Workers and Its Decisions (Hamburg: International of Seamen and Harbour Workers, 1932).
5. Adi, Hakim, “The Comintern and Black Workers in Britain and France 1919–37,” Immigrants and Minorities 28, nos. 2–3 (2010): 224–245.