R.R. Bowker Company, 1986
Buku Referensi
R.R. Bowker Company, 1986
Buku Referensi
edited by Victor Burgin, James Donald and Cora Kaplan
Routledge, 1989
Buku Teks SO
Hunt, Peter, 1945-
Oxford University Press, 1994
Buku Teks SO
Geldard, Kathyrn
Sage, 2002
Buku Teks SO