Rossman, Gretchen B.
Sage, 2003
Buku Teks
Norman K. Denzin, editor; Yvonna S. Lincoln, editor
Sage Publications, 2003
Buku Teks
Schratz, Michael
Routledge, 1995
Buku Teks
Sage Publications, 2000
Buku Referensi
Marshall, Catherine
Sage, 1999
Buku Teks