Carter, L.R., author
John Wiley & Sons, 1973
Buku Teks
Young, Dona J., author
McGraw-Hill, 2006
Buku Teks
Henn, Stephen K., author
Wiley, 2009
Buku Teks
Kaplan, A.D.H., author
Brookings Institutions, 1959
Buku Teks
Moore, Gary A., author
South-western Publishing, 1987
Buku Teks