Lubeck, Steven G.
Aldine Publishing Company, 1971
Buku Teks
Macintyre, Stuart, author
Australian Goverment, 1947
Buku Teks
Wilson, Earl R., author
McGraw-Hill Book , 1999
Buku Teks
Wilson, Earl R., author
McGraw-Hill, 2004
Buku Teks
Tenner, Irving, author
Prentice-Hall, 1960
Buku Teks