Bolander, Donald O., author
Career Publishing, 1992
Buku Referensi
Radin, Max
St Paul Minn, 1936
Buku Teks
Buhler, Michael W, author
Sweet & Maxwell, 2005
Buku Teks
Hemphill, Charles F., author
Prentice-Hall, 1980
Buku Teks
Scott-Kilvert, Ian, author
Longmans, Green, 1970
Buku Teks