Clymo, R. S, author.
Cambridge University Press, 2014.
Buku Teks
Makarenko, A.S., author
Foreign Languages Publishing House, 1920
Buku Teks
Anderson, Chris, author
Headline Publishing Group, 2016
Buku Teks
Houston, Brant, author
St. Martin Press, 1996
Buku Referensi
Arnold, Alvin L.
Warren, Gorham and Lamont, Inc., 1971
Buku Teks