Haeoe Munhwa Hongbowon
Korean Culture and Information Service, 2011
Buku Teks
Grimme, Don, author
American Management Association, 2009
eBooks
Mariotti, John, author
Capstone, 2004
Buku Teks
Frieman, Barry B., author
McGraw-Hill, 2001
Buku Teks
Harderer, Michael, author
OPEC Secretariat, 2011
Buku Referensi