sle of Man,, 1994
Buku Teks
edited by S.I. Hayakawa; revised by P.J. Fletcher
Cassell , 1981
Buku Referensi
Edited by Norbert Pachler; Ana Redondo
Routledge, 2007
Buku Teks
Smith, Jennifer, author
Macmillan, 1982
Buku Teks
Pyle, Michael A., author
Lincoln : Nebraska, 1991,
Buku Teks