Bowie, Robert R
ColumbiaUniversity Press, 1964
Buku Teks
Whiting, Allen S., author
Stanford University Press, 1981
Buku Teks
Hsieh, Alice Langley, author
Prentice-Hall, 1962
Buku Teks
Rostow, Walt Whitman, author
Cambridge University Press, 1971
Buku Teks
Vanhanen, Tatu, author
Routledge, 1997
Buku Teks