Bullard, Reader
Oxford university Press, 1958
Buku Teks
Morrison, Stanley Andrew, author
SCM Press, 1954
Buku Teks
Stocking, George W., author
Vanderbilt University Press, 1970
Buku Teks
Carlson, Paul A., author
South Western, 1957
Buku Teks
edited by E.M. Kirkpatrick ; assistant editors, C.M. Schwarz ... [and others]
Chambers, 1983
Buku Referensi