Robert C. Arffa
John Wiley & Sons, 2001
Buku Teks
Egan, Mike, author
McGraw-Hill, 2012
Buku Teks
Paul, Karamjeet, author
Academic Press, 2014
eBooks
editors: Grant Harman
UNESCO, 1991
Buku Teks
Wahyu Putranto, author
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2012
UI - Skripsi (Open)