Sofia, 1981
Buku Teks
Commons, John R.
Macmillan, 1956
Buku Teks
Park, Jae Dong
Hangyorae Chulpan, 2007
Buku Teks
Eliot, Charles William, 1834-1926, author
Routledge & Kegan Paul, 1954
Buku Teks
Gieser, Carl Richard, author
Summer Institute of Linguistics, 1963
Buku Teks