Merrett, A.J., author
Longman , 1963
Buku Teks
Rosovsky, Henry, author
Free Press, 1961
Buku Teks
Sharpe, William F., author
McGraw-Hill, 2000
Buku Teks
Dougall, Herbert E., author
Prentice-Hall, 1975
Buku Teks
Dougall, Herbert E., author
Prentice-Hall, 1965
Buku Teks