United Nations Environment Programming (UNEP). (1993). Cleaner production worldwide. UNEP.
Chicago Style aipamenaUnited Nations Environment Programming (UNEP). Cleaner Production Worldwide. Paris: UNEP, 1993.
MLA aipamenaUnited Nations Environment Programming (UNEP). Cleaner Production Worldwide. UNEP, 1993.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.