Schiller, Bradley R., author
Prentica-Hall , 1975
Buku Teks
Reynold, Lloyd George
McGraw-Hill, 1981
Buku Teks
Colm, Gerhard, author
National Planning Association , 1961
Buku Teks
Zabel, William D.
William Morrow and Company, Inc., 1995
Buku Teks
Melman, Seymour, author
Simon and Schuster , 1974
Buku Teks