Gray, James, Sir, 1891-1975., author
Cambridge University Press, 2013
Buku Teks
Kendeigh, S. Charles
Prentice-Hall, 1975
Buku Teks
Fox, Michael W.
University Park Press, 1983
Buku Teks
Andrew Timothy Umboh, author
Univesitas Indonesia. Fakultas Ilmu Sosial Dan Politik, 2018
UI - Tugas Akhir
edited by Peter Messent and Donald Broom
Grolier International, 1993
Buku Referensi