Morris, Richard J., author
Scott, Foresman, 1985
Buku Teks
Telford, Charles Witt, author
Prentice-Hall, 1981
Buku Teks
edited by Jane Henry
Routledge, 2005
Buku Teks
Smith, Robert M., author
McGraw-Hill, 1975
Buku Teks
Levinson, Harry, author
Harvard University Press, 1971
Buku Teks