Caldwell, Wallace Everett, author
Holt, Rinehart and Winston, 1963
Buku Teks
Blois, Lukas de, author
Routledge, 1997
Buku Teks
Armstrong, A.H., author
Newman Press, 1949
Buku Teks
Maine, Henry Sumner, 1822-1888, author
J.M. Dent & Sons, 1954
Buku Teks
Caldwell, Wallace Everett, author
Holt, Rinehrt and Winston, 1963
Buku Teks