Robert, Collins, author
Harper Collins, 1995
Buku Referensi
Lambert, Rene, author
Ce?padues-Editions, 1991
Buku Referensi
edited by Marie-Helene Correard
Oxford University Press, [Date of publication not identified]
Buku Referensi
English Universities Press, 1955
Buku Referensi
de Vries, Louis, author
McGraw-Hill, 1951
Buku Referensi