Kupper, Heinz, author
Classen, 1964
Buku Referensi
Brugger S.J., Walter, author
Wieh Herder 1948
Buku Referensi
Methuen & Co. ; Langenscheidt Kg., 1962
Buku Referensi
Methuen & Co. ; Langenscheidt Kg., 1963
Buku Referensi
Gayed, Riad, author
Elia's Modern Press, [date of publication not identified]
Buku Referensi