Fraser, George Sutherland, 1915-
Published for the British Council and the National Book League by Longmans, 1965
Buku Teks SO
Marjorie Howes, John Kelly, editor
Cambridge University Press, 2008
Buku Teks SO
Shannon, William V.
Macmillan, 1963
Buku Teks SO
Shannon, Robert E.
John Wiley & Sons, 1980
Buku Teks
Shannon, David A.
Macmillan, 1995
Buku Teks SO