Não informado. (1969). WHO library acquisitions. World Health Organization.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. WHO Library Acquisitions. Geneva, Suíça: World Health Organization, 1969.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. WHO Library Acquisitions. World Health Organization, 1969.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.