Artikel Jurnal
edited by Howard Giles and W. Peter Robinson
John Wiley & Sons, 1990
Buku Referensi
Devito, Joseph A.
Random House, 1970
Buku Teks
Field, John
Routledge, 2005
Buku Teks SO
Lemke, J.L. (Jay L.)
Oxford University Press, 1989
Buku Teks SO