Ball, Rodney
Routledge, 1997
Buku Teks
Hernandez-Campoy, Juan Manuel, author
Wiley Blackwell, 2016
Buku Teks
Fennell, Barbara A., author
Blackwell Publishers, 2001
Buku Teks
Abrahamson, Mark, author
Prentice-Hall, 1981
Buku Teks
Egmose, Jonas, author
Routledge, 2015
Buku Teks