Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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