Gordon, Robert Aaron, author
Columbia University Press, 1959
Buku Teks
UNESCO, 1978
Buku Teks
Ministry of Education, 1994
Buku Teks
Lewis, Ralph G., author
St. Lucie Press, 1994
Buku Teks
McCorkle, Chester O., author
Jossey-Bass Publishers, 1982
Buku Teks