Baah, Asamoah
World Health Organization, 1995
Buku Teks
edited by Kenneth Lee, Anne Mills
Oxford University Press, 1984
Buku Teks
Phelps, Charles E., author
Harper Collins, 1992
Buku Teks
Donaldson, Cam, author
Macmillan, 1994
Buku Teks
Akin, John S., author
World Bank, 1987
Buku Teks