Angle, Paul M.
Rand McNally , 1958
Buku Teks
Bardes, Barbara A., author
Thomson/Wadsworth, 2006
Buku Teks
Starratt, Edith E.
Prentice-Hall, 1966
Buku Teks
Luard, Evan, author
St. Martin`s Press, 1992
Buku Teks
Corwin, Edward S., author
New York University Press, 1956
Buku Teks