Lougheed, Leslie Alan
Penguin Books, 1988
Buku Teks SO
Williams, Morris
Longman, 1972
Buku Teks SO
by J. Swiericzuk ... [and others]
Pitman, 1980
Buku Teks
edited by Gordon Greenwood and Norman Harper
F.W. Cheshire, 1957
Buku Teks SO
edited by Greg Crouch, Ted Wheelwright, Ted Wilshire
Penguin Books, 1980
Buku Teks SO