KPPI and Word Bank, 2003
Buku Teks
Palumbo, Dennis J., author
Harcourt Brace College, 1994
Buku Teks
McNichols, Thomas J., author
McGraw-Hill, 1967
Buku Teks
McNichols, Thomas J., author
McGraw-Hill, 1972
Buku Teks
Brook, Penelope J., author
The World Bank, 2003
Buku Teks