Yearn, Hong-choi
Shinkwang Publishing, 2008
Buku Teks
Jeong, Gu Hyeon.
Wisdom House, 2008
Buku Teks
Barrow, Christopher J.
Routledge, 2006
Buku Teks
editor, Gunter Schramm and Jeremy J. Warford
The World Bank, 1991
Buku Teks
The World Bank, [date of publication not identified]
Buku Teks