by Mitch Blair ... [et al.]
Oxford University Press, 2004
Buku Teks
Combs, Gerald F., author
Elsevier/Academic Press, 2012
Buku Teks
The World Bank, 1997
Buku Teks
New York : Macmillan, 1993,
Buku Referensi
World Health Organization
World Health Organization, 1996
Buku Teks