Rees, Colin
Churchill Livingstone/Elsevier, 2012
Buku Teks SO
edited by David M. Fetterman
Jossey Bass, 1991
Buku Teks SO
Glaser, Barney G.
Aldine, 1967
Buku Teks SO
edited by Catherine Cassel and Gillian Symon
Sage, 1994
Buku Teks SO
edited by Catherine Cassel and Gillian Symon
Sage, 1995
Buku Teks SO