Hope, Wayne, author
Palgrave Macmillan, 2016
Buku Teks
Halliday, Jon, author
Pantheon Books, 1975
Buku Teks
Harrington, Michael, 1928-1989
Simon and Schuster, 1976
Buku Teks
Dobb, Maurice, author
International Publishers, 1947
Buku Teks
Sage Publications, Inc, 2005
Majalah, Jurnal, Buletin