Hill, John William, 1933-, author
Upper Saddle RIver Prentice Hall 1997,
Buku Teks
Lane, Frederick A
Aladdin Books, 1954
Buku Teks
Fall, Bernard B.
Doubleday, 1967
Buku Teks
Haspeslagh, Philippe C.
N.Y. The Free Press, 1991
Buku Teks
McColvin, Eric, author
Longmans, Green and Co., 1946
Buku Teks