Platt, Nathaniel, author
Prentice-Hall, 1964
Buku Teks
Oldenbourg, Zoe
Pantheon Books, 1965
Buku Teks
Huntington Caims, John Walker, edited
Macmillan, 1952
Buku Referensi
Speyer, Edward, author
John Wiley & Sons, 1994
Buku Teks
Roberts, Ann, author
Routledge, 2007
Buku Teks