APA (7e ed.) Bronvermelding

(1990). Diseases of the digestive system. World health organization.

Chicago (17e ed.) Bronvermelding

Diseases of the Digestive System. Ginebra: World health organization, 1990.

MLA (9e ed.) Bronvermelding

Diseases of the Digestive System. World health organization, 1990.

Let op: Deze citaties zijn niet altijd 100% accuraat.