Evans, Graham, author
Harvester Wheatsheaf, 1990
Buku Referensi
edited by Tim O`Riordan and Jill Jager
Routledge, 1996
Buku Teks
Merriam, Charles E. (Charles Edward), author
New York University Press, 1936
Buku Teks
Dahl, Robert A., 1915-2014, author
Harper & Brothers , 1953
Buku Teks
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2012
UI - Skripsi (Open)