Rossman, Gretchen B., author
Sage, 2003
Buku Teks
Grbich, Carol, author
Allen and Unwin, 1999
Buku Teks
Kvale, Steinar
SAGE Publications, 1996
Buku Teks
Brinkmann, Svend, author
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Buku Teks
Punch, Keith F., author
SAGE Publications, 1998
Buku Teks