Velikoretsky, A.
Foreign Languages Publishing House , T.t.
Buku Teks
Beamish, Paul W., 1953-, author
Irwin, 1997
Buku Teks
Hinchliffe, Arnold P., 1930-, author
Macmillan, 1985
Buku Teks
Page, Malcolm, author
Macmillan Education, 1987
Buku Teks
Huxley, Phil, author
Blackstone Press Limited, 1998
Buku Referensi