Heumann, William L.
McGraw-Hill, 1997
Buku Teks
Gautreau, Ronald, author
McGraw-Hill, 1978
Buku Teks
Fellner, William, 1905-, author
American Enterprise Institute, 1981
Buku Teks
Nash, William A., author
McGraw-Hill, 1957
Buku Teks
Nash, William A., author
McGraw-Hill, 1972
Buku Teks