The National Institute of The Korean Language, 2011
Buku Teks
Atiyah, Edward, author
Penguin Books, 1958
Buku Teks
Bradshaw, Michael J, author
McGraw-Hill, 2012
Buku Teks
Kelter, Paul B., author
McGraw-Hill, 2003
Buku Teks
Paris : The United Nations Educational
Majalah, Jurnal, Buletin