* [http://www.spartacus.schoolnet.co.uk/USAfosterW.htm Spartacus - William Z. Foster]
* [http://www.spartacus.schoolnet.co.uk/USAfosterW.htm Spartacus - William Z. Foster]
* [http://www.wsws.org/history/1996/feb1996/foster.shtml WSWS - The Life of William Z. Foster]
* [http://www.wsws.org/history/1996/feb1996/foster.shtml WSWS - The Life of William Z. Foster]
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* Alexander and Earl to Foster, RTsKhIDNI 534-6-137, 11 July, 1928;
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* ''The Soviet World of American Communism'', Harvey Klehr, John Earl Haynes, Kyrill M. Anderson, Yale University Press, 1996, p. 187, 190, Document 54.