Silverman, David, author
Sage Publications , 2010
Buku Teks
Norman K. Denzin, Yvonna S. Lincoln, editors
Sage Publications, 2000
Buku Referensi
Silverman, David, author
Sage, 2000
Buku Teks
Gorman, G.E., author
Facet Publishing, 2005
Buku Teks
SAGE publications, 2010
Buku Teks