Sage Publications, 2008
eBooks
Haenssgen, Marco J., author
Emerald Publishing Limited, 2019
eBooks
Neuman, William Lawrence, 1950-, author
Pearson Education, 2014
Buku Teks
Brinkmann, Svend, author
Sage Publications , 2015
Buku Teks
Creswell, John W., author
Pustaka Pelajar, 2009
Buku Teks