Shepherd, Geoffrey S.
Iowa State University Press, 1968
Buku Teks
Means, Gardiner C.
Harper & Brothers Publishers, 1962
Buku Teks
Williams, Stephen F.
American Enterprise Institute for Public Policy Research, 1985
Buku Teks
Cochrane, Willard W.
University of Minnesota Press, 1964
Buku Teks
Mills, Frederick C.
The National Bureau of Economic Research, Inc. , 1936
Buku Teks