Huseman, Richard C., author
Allyn and Bacon, 1977
Buku Teks
Hayes, James L., author
Amacom , 1983
Buku Teks
Cummings, L.L., author
Richard D. Irwin, 1980
Buku Teks
edited by Jack C. Richards
Longman, 1993
Buku Teks
Herbert, Theodore T., author
Macmillan, 1976
Buku Teks