Gianessi, Leonard P.; Reigner, Nathan P. (2007 4월). “The Value of Herbicides in U.S. Crop Production”. 《Weed Technology》 21 (2): 559–566. doi:10.1614/WT-06-130.1. S2CID86114859.다음 날짜 값 확인 필요: |date= (도움말)
Gianessi, Leonard P.; Reigner, Nathan P. (2007 4월). “The Value of Herbicides in U.S. Crop Production”. 《Weed Technology》 21 (2): 559–566. doi:10.1614/WT-06-130.1. S2CID86114859.다음 날짜 값 확인 필요: |date= (도움말)