Indicators of oligotrophy : 800 taxa representative of three ecologically distinct lake types : carbonate buffered, oligodystrophic, weakly buffered soft water = Oligothophie-Indikatoren : 800 taxa repräsentativ für drei diverse seen-typen : lalkreich-oligodystroph-schwach gepuffertes weichwasser - Lange-Bertalot, Horst (Iconographia diatomológica. Annotated diatom micrographs / edited by Horst Lange-Bertalot, 1996)