Fudulu,Paul, author
Emerald, 2017
eBooks
edited by Stewart Sutherland, Leslie Houlden, Peter Clarke, Friedhelm Hardy
Routledge, 1988
Buku Referensi
prepared by the Cartographic Department of the Clarendon Press
Oxford University Press, 1972
Buku Referensi
Euromonitor, 1989
Buku Teks
Todaro, Michael P., author
Longman, 1989
Buku Teks