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Dyfyniad Arddull ChicagoWorld Health Organization. Cancer Pain Relief: With a Guide to Opioid Availability. Geneva: World Health Organization, 1996.
Dyfyniad MLAWorld Health Organization. Cancer Pain Relief: With a Guide to Opioid Availability. Geneva: World Health Organization, 1996.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.