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
Pink, Sarah, author
Sage Publications , 2002
Buku Teks