Channon, John, author
Penguin Books, 1995
Buku Referensi
Shepperd, William R., author
Barnes and Noble, 1959
Buku Referensi
Land resources Departement NRI overseas development administration foreign communication wealth office U.K., 1990,
Buku Referensi
Roolvink, R., author
Djambatan, 1957
Buku Referensi
Davies, Cuthbert Collin, 1896-1974, author
Oxford University Press, 1959
Buku Teks