Gramedia Pustaka Utama, 2005
Buku Teks
Thomas, Joseph
Philadelphia : J.B. Lippincott, 1915
Buku Referensi
Hartmann, Reinhard R.K.
Routledge, 1998
Buku Referensi
Himus, Godfrey W.
Harmondsworth, Middlesex, 1954
Buku Referensi
Los Angeles : John C. Winston, 1942
Buku Referensi