Laski, Harold J.
George Allen and Unwin, 1946
Buku Teks
Wolf, Robert Lee
The Norton Library, 1967
Buku Teks
New York [etc.] Harper 1947
Buku Teks
Grosser, Maurice
Charter Books, 1964
Buku Teks
Myers, Bernard S.
Oxford University Press, 956.
Buku Teks