McDonald, Bryan L., author
Oxford University Press, 2017
eBooks
Barnett, A. Doak (Arthur Doak), author
Overseas Development Council, 1979
Buku Teks
Tudge, Colin
Dorling Kindersley, 2002
Buku Teks
Indonesian agency for agricultural research and development,
Majalah, Jurnal, Buletin
edited by Ben Mephan
Routledge , 1996
Buku Teks