Artikel Jurnal
Francis, John de, author
Princeton University Press , 1950
Buku Teks
edited by Ralph C. Staiger
UNESCO, 1973
Buku Teks
edited by J. Charles Alderson and A.H. Urquhart
Longman, 1992
Buku Teks
Fairbairn, Gavin, author
McGraw-Hill, 2012
Buku Teks