Thompson, Anthony, author
UNESCO, 1983
Buku Referensi
Mellon, Constance A., author
Greenwood Press, 1990
Buku Teks
edited by Richard Parncutt and Gary E. McPherson
Oxford University Press, 2002
Buku Teks
Lessing, Doris
Simon and Schuster, 1961
Buku Teks
Bond, Brian
Oxford University Press, 1996
Buku Teks