Gaya APA
Population, resources, environment and development data bank (pred bank version 3.0). (2002).
America:
United Nations.
Gaya Chicago
Population, resources, environment and development data bank (pred bank version 3.0).
.
America:
United Nations,
2002.
.
Gaya MLA
Population, resources, environment and development data bank (pred bank version 3.0).
.
America:
United Nations,
2002.
.
Gaya Turabian
Population, resources, environment and development data bank (pred bank version 3.0).
America:
United Nations,
2002.
.