Helgeson, E. A. (1957). Methods of weed control. Food and Agriculture Organization of the United Nations.
Citazione stile Chigago Style (17a edizione)Helgeson, Earl A. Methods of Weed Control. Rome: Food and Agriculture Organization of the United Nations, 1957.
Citatione MLA (9a ed.)Helgeson, Earl A. Methods of Weed Control. Food and Agriculture Organization of the United Nations, 1957.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.