edited by Terence H. Hull
ISEAS, 2005
Buku Teks
Cook, Robert C., author
Population Council, 1968
Buku Teks
Birrell, Robert, author
Longman Cheshire, 1987
Buku Teks
Sweezy, Alan
California The California Institute of Technology 1973
Buku Teks
American Association for the Advancement of Science, 1975
Buku Teks