Todd, Lewis Paul
Harcourt Brace Jovannovich, 1972
Buku Teks
Patrick, John
Macmillan Publishing Company, 1984
Buku Teks
Diggins, John Patrick
W.W Norton, 1992
Buku Teks SO
Alden, John Richard
Harper & Row Publishers, 1963
Buku Teks
Kenichi Ohmae
The Free Press, 1995
Buku Teks