Menge, Herman, author
Berlin Langenscheidt 1961
Buku Referensi
Klatt, Edmund
Berlin Langenscheidt KG. Verlag buchhandlung 1961
Buku Referensi
London, London Longmans
Buku Referensi
London, 1982
Buku Referensi
Lewis, Charlton T., author
New York American Book 1918
Buku Referensi