Problems of sampling in trace element investigations.
D000704:Analysis of Variance; D004782:Environmental Health; D005618:Fresh Water; D055593:Geological Phenomena; D005844:Geology; D008923:Missouri; D012494:Sampling Studies; D013223:Statistics as Topic; D014131:Trace Elements / Q000032:analysis*; D014867:Water / Q000032:analysis*
D014131:Trace Elements; D014867:Water