Possible problems are discussed and guidelines for correct use are given.doi:10.1046/j.1365-3180.1997.d01-70.xM. HESSG. BARRALISH. BLEIHOLDERL. BUHRR. STAUSSJohn Wiley & Sons, Ltd (10.1111)Weed ResearchHess, M.; Barralis, G.; Bleiholder, H.; Buhr, L.; Eggers, T.H.; Hack, H....