Morris, Schaefer
World Health Organization, 1999
Buku Teks
WHO , 1979
Buku Teks
Gray, Stephen E.
MacMillan Press , 1978
Buku Teks
Smolensky, Jack
W B Saunders company, 1972
Buku Teks
Herman, Harold
International City Managers Association, 1968
Buku Teks