Beveridge, Wilbert Esler, author
Allen & Unwin, 1975
Buku Teks
Maier, Norman R.F.
John Wiley & Sons, 1960
Buku Teks
Cambridge University Press, 1997
eBooks
Fiza Fitra Dini, author
Universitas Indonesia, 2009
UI - Tesis (Open)
Fletcher, John, author
Duckworth, 1973
Buku Teks