JTart Publishing & Media, 2012
Buku Referensi
McElroy, Mark W., author
Butterworth-Heinemann, 2003
Buku Teks
Addison-Wesley, 1976
Buku Teks
Goodnow, Henry Frank
Yale University Press 1, 1964
Buku Teks
Lipset, Seymour Martin, author
Basic Books, 1963
Buku Teks