Ahlgren, G. H., Kingman, G. C., & Wolf, D. E. (1951). Principles of weed control. John Wiley & Sons INC.
Dyfyniad Arddull ChicagoAhlgren, Gilbert H., Glenn C. Kingman, and Dale E. Wolf. Principles of Weed Control. NewYork: John Wiley & Sons INC, 1951.
Dyfyniad MLAAhlgren, Gilbert H., et al. Principles of Weed Control. John Wiley & Sons INC, 1951.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.