Svensen, Bo, author
Cambridge University Press, 2009
Buku Teks
edited by Martin E. Liggins, David L. Hall, James Llinas
CRC Press, 2009
Buku Referensi
Searles, William H., author
John Wiley & Sons, 1949
Buku Referensi
Armstrong, Michael, author
Kogan Page Limited, 1995
Buku Referensi
edited by John S. Dryzek, Bonnie Honig, Anne Phillips
Oxford University Press, 2008
Buku Referensi