UNESCO, 1989
Buku Referensi
World Health Organization
World Health Organization, 1976
Buku Teks
United Nation. Departement of Economic and Social Affairs. Statistical Office
United Nation, 1957
Buku Referensi
Stols, AAM
La Haye [etc.] Edition AAM Stols 1946
Buku Teks
United Nations
United Nations, 1990, c1991, c1994
Buku Teks