Schratz, Michael, author
Routledge, 1995
Buku Teks
Rossman, Gretchen B., author
Sage, 2003
Buku Teks
Berg, Bruce L. (Bruce Lawrence), 1954-, author
Pearson, 2014
Buku Teks
Marshall, Catherine, author
Sage, 1999
Buku Teks
Sage Publications, 2000
Buku Referensi