Marion Wesley Todd
Macmillan, 1934
Buku Teks
Schwab, Glenn Orville, 1919-, author
New York: John Wiley & Sons, 1957
Buku Teks
Peters, Max, author
McGraw-Hill, 1984
Buku Teks
Clayton, Albert E., author
Longmans, 1966
Buku Teks
Broek, David, author
Martinus Nijhoff, 1982
Buku Teks