Cohen, Jack
Penguins Books, 1994
Buku Teks
O`Donnell, Sandra Martin
Prentice-Hall, 1994
Buku Teks
Krogh, David
Pearson, 2009
Buku Teks
Cotterill, Rodney
Cambridge University Press, 1989
Buku Referensi
edited by Gerald W. Whitted
Pan American World Airways, 1971
Buku Referensi