Columbia : Columbia University Press and American Dialect Society
Majalah, Jurnal, Buletin
Levy, Leonard W.
Harper, 1963
Buku Teks SO
Ladefoged, Peter
Blackwell, 2001
Buku Teks SO
Buckley, Lillian A.
Citation Press, 1975
Buku Teks
Seoul Selection, 2011
Buku Teks SO