Europe Publications, 1992
Buku Referensi
Kraus, Herbert
Schimmelbusch, 1953
Buku Teks
Kaminski, Winfred
Weinheim und Munchen Juventa 1998
Buku Teks
Ferguson, Wallace K., author
Sir Isaac Pitman & Sons, [date of publication not identified]
Buku Teks
Kamen, Henry, author
Routledge, 2000
Buku Referensi