RIddle, K. Wilkinson, author
London Arco 1962
Buku Referensi
Echols, John M., editor; Hassan Shadily, 1920-
Gramedia Pustaka Utama, 2005
Buku Teks
Himus, Godfrey W., author
Harmondsworth, Middlesex, 1954
Buku Referensi
Los Angeles : John C. Winston, 1942
Buku Referensi
Hartmann, Reinhard R.K., author
Routledge, 1998
Buku Referensi