edited by David Bloomfield, Teresa Barnes, and Luc Huyse ; contributors, David Bloomfield [and others]
International IDEA, 2003
Buku Teks
editors, Dan Landis, Rosita D. Albert
Springer, 2012
eBooks
Holt, Stephen
Hamish Hamilton, 1967
Buku Teks
Armstrong, Michael
Kogan Page Limited, 1995
Buku Referensi
Dudek, Susan G.
J.B. Lippincott, 1997
Buku Teks SO