APA (7e ed.) Bronvermelding

Helgeson, E. A. (1957). Methods of weed control. Food and Agriculture Organization of the United Nations.

Chicago (17e ed.) Bronvermelding

Helgeson, Earl A. Methods of Weed Control. Rome: Food and Agriculture Organization of the United Nations, 1957.

MLA (9e ed.) Bronvermelding

Helgeson, Earl A. Methods of Weed Control. Food and Agriculture Organization of the United Nations, 1957.