Spicker, Paul
Prentice-Hall, 1995
Buku Teks
University of Kansas , 1981
Buku Teks
Tavistock Publications, 1970
Buku Teks
Finegan, Edward, author
Cambridge University Press, 2006
Buku Teks
Becker, Edward F., author
Cambridge University Press, 2012
Buku Teks