Cohen, Jack
Penguins Books, 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
Shore, Peter
Bernard Babani, 1995
Buku Referensi