Bullard, Reader
Oxford university Press, 1958
Buku Teks
edited by Peter Mansfield
Oxford University Press, 1973]
Buku Teks
Royal Institute of International Affairs, 1954
Buku Teks
Morrison, Stanley Andrew, author
SCM Press, 1954
Buku Teks
Stocking, George W., author
Vanderbilt University Press, 1970
Buku Teks