Crystal, David, 1941-
Westview Press, 1980
Buku Referensi
Trask, R.L.
Routledge, 1996
Buku Referensi
Pei, Mario A.
Philosophical Library, 1954
Buku Referensi
Pei, Mario A.
Totowa, New Jersey Littlefield, Adams 1975
Buku Referensi
Pei, Mario A.
Peter Owen, 1958
Buku Referensi