Knorr, K.E., author
Stanford University Press, 1945
Buku Teks
Phillips, Charles F., author
University of North Carolina , 1963
Buku Teks
editors, P. Schidrowthz, T.R. Dawson
W. Heffer and Sons, 1952
Buku Teks
Bauer, P. T., author
Harvard University Press, 1948
Buku Teks
Thomas, Kenneth D.
[publisher not identified], [date of publication not identified]
Buku Klasik