David Collier, John Gerring, editor
Routledge, 2009
Buku Teks
Scholz, Roland W.
Sage, 2002
Buku Teks
Norman K. Denzin, editor; Yvonna S. Lincoln, editor
Sage Publications, 2003
Buku Teks
Mikes Saks, Judith Allshop, editor
Sage, 2019
Buku Teks
Neuman, Lawrence W.
Pearson New International edition, 2014
Buku Teks