Savage, Donald T., author
John Wiley & Sons, 1977
Buku Teks
Barger, Harold, author
Rand McNally, 1969
Buku Teks
Auerbach, Robert D., author
Macmillan, 1989
Buku Teks
Miller, Roger LeRoy, author
McGrow-Hill, 1985
Buku Teks
Steiner, William Howard, author
Henry Holt, 1956
Buku Teks