Hart, Chris, author
Sage Publications, 2007
Buku Teks
Druckman, Daniel, author
Sage Publications, 2005
Buku Teks
Bruns, Bettina
VS Verlag, 2012
eBooks
Greenlaw, Steven A., author
South Western, Cengage Learning, 2009
Buku Teks
Bell, Judith, author
McGraw-Hill Education, 2014
Buku Teks