Johnson, Harry G., author
Harvard University Press , 1967
Buku Teks
Halm, George N., author
University of North-Carolina Press, 1945
Buku Teks
Coffey, Peter, author
Macmillan, 1974
Buku Teks
Robertson, D.H., author
Staples Press, 1948
Buku Teks
Mints, Lloyd W., author
McGraw-Hill, 1950
Buku Teks