Creswell, John W., author
Sage, 1998
Buku Teks
Creswell, John W., author
SAGE Publications, 2018
Buku Teks
Patton, Michael Quinn, author
Sage, 1990
Buku Teks
Norman K. Denzin, editor; Yvonna S. Lincoln, editor
Sage Publications, 2003
Buku Teks
Strauss, Anselm L., author
Cambrigde University Press, 1987
Buku Teks