Artikel Jurnal
Beckhard, Richard, author
Addison-Wesley, 1987
Buku Teks
Bassani, F., author
Pergamon Press, 1975
Buku Teks
Nowo Riveli, author
Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2007
UI - Tesis (Membership)
edited by, Guillermo O`Donnell, Philippe C. Schmitter and Laurence Whitehead
The Johns Hopkins University Press, 1989
Buku Teks