Paul M. Camic, Jean E. Rhodes, Lucy Yardley
APA, 2007
Buku Teks
Marczyk, Geoffrey, author
John Wiley & Sons, 2005
Buku Teks
edited by George Mckenzie, Jackie Powell, Robin Usher
The Falmer Press, 1997
Buku Teks
Creswell, John W., author
Sage Publication, Inc, 2003
Buku Teks
Creswell, John W., author
Sage, 2018
Buku Teks