Collier, John G. (John Greenwood), author
Cambridge University Press, 1987
Buku Teks
Henn, Harry, Alexander, John R
St.Paul,Minn : West publishing Co, 1983,
Buku Referensi
Watkins, Eric, author
Cambridge University Press, 2019
eBooks
Pan, Guoping
Intercontinental Press, 2010
Buku Teks
Hay, Peter, author
West Publishing, 1994
Buku Teks