Wolf, Robert Lee
The Norton Library, 1967
Buku Teks
New York [etc.] Harper 1947
Buku Teks
Grosser, Maurice, author
Charter Books, 1964
Buku Teks
Myers, Bernard S., author
Oxford University Press, 956.
Buku Teks
Laski, Harold J., author
George Allen and Unwin, 1952
Buku Teks