Holes, Clive, author
Longman, 1995
Buku Teks
Owen, W. V.
Ronald Press, 1958
Buku Teks
Certo, Samuel C.
Allyn and Bacon, 1989
Buku Teks
Salaman, Redclife N., author
Cambridge University Press, 2014
Buku Teks
Whittaker, E.T.
Cambridge University Press, 1965
Buku Teks