(1991). Report of the twenty first session London, 18-22 february, 1991. [s.l.]: World Health Organization.
Citación estilo ChicagoReport of the Twenty First Session London, 18-22 February, 1991. [s.l.]: World Health Organization, 1991.
Cita MLAReport of the Twenty First Session London, 18-22 February, 1991. [s.l.]: World Health Organization, 1991.
Precaución: Estas citas no son 100% exactas.