APA aipamena

Valverde, R. (2003). Access to drinking water in Costa Rica.

Chicago Style aipamena

Valverde, Ricardo. Access to Drinking Water in Costa Rica. 2003.

MLA aipamena

Valverde, Ricardo. Access to Drinking Water in Costa Rica. 2003.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.