Harrod, R.F., author
Macmillan, 1956
Buku Teks
Choudhury, Masudul Alam, 1948-, author
Routledge, 2017
eBooks
Preiss, Julian, author
Routledge, 2013
Buku Teks
Spulber, Nicolas
Indiana Univeristy Press , 1965
Buku Teks
Townsend, Harry, author
Routledge , 1995
Buku Teks