Newbrander, William, author
World Health Organization, 1992
Buku Teks
Nafziger, E. Wayne, author
Prentice-Hall, 1990
Buku Teks
Myint, Hla, author
Hutchinson University Library, 1973
Buku Teks
edited by Kenneth Lee, Anne Mills
Oxford University Press, 1984
Buku Teks
Akin, John S., author
World Bank, 1987
Buku Teks