World Health Organization, 1987
Buku Teks
Cummings, William K., author
International Development Research Center, 1986
Buku Teks
Slate, Floyd O.
Cornell University, 1974
Buku Referensi
World Health Organization, 2003
Buku Teks SO
Lewin, A. C.
John Wiley & Sons, 1981
Buku Teks