Nicolai, Katherine, author
Thomson Wadsworth, 2005
Buku Teks
Impact Books, 1993
Buku Referensi
edited by Marie-Helene Correard
Oxford University Press, [Date of publication not identified]
Buku Referensi
Neather, E.J.
MacMillan Press , 1985
Buku Teks
Lambert, Rene, author
Ce?padues-Editions, 1991
Buku Referensi