Wilson, Paul R.
George Allen and Unwin, 1982
Buku Teks
Brower, Anne C.
Elsevier/Saunders, 2012
Buku Teks SO
edited by David Dabydeen
Manchester University Press, 1985
Buku Teks SO
Berndt, Ronald M.
F.W. Cheshire, 1951
Buku Teks SO
Bennett, Lerone
Penguin Books, 1969
Buku Teks SO