Marden, Charles Frederick.
American Book Co, 1968
Buku Teks
Morison, Samuel Eliot, author
Oxford University Press, 1962
Buku Teks
Norton, 1967
Buku Teks
American Library Association , [date of publication not identified]
Buku Teks
Holt, Rinehart and Winston, 1966
Buku Referensi