Ludowyk, E.F.C., author
Frederick A. Praeger, 1966
Buku Teks
Trautz, F.M.
Munchen Muller 1926
Buku Teks
Arasartnam, Sinnappah, author
Prentice-Hall, 1964
Buku Teks
Bailey, Sydney D., author
William Brendon ans Son, 1952
Buku Teks
Brohier, R.L.
Lake House Investments, 1971
Buku Teks