Fitzgerald, C.P.
Oxford University Press, 1965
Buku Teks
Latz, Gil, author
John Wiley & Sons, 1996
Buku Referensi
edited by Allan Nevins and Louis M. Hacker
D.C. Heath, 1943
Buku Teks
Grigg, Edward, Sir, author
Liveright Publishing Corporation, 1944
Buku Teks
Stillman, William, author
Jossey-Bass, 2009
Buku Teks