lehdissä
Lehdissä is the inessive plural form of the Finnish noun lehti. The base lehti can mean either a newspaper or a leaf/leaflet, so lehdissä translates roughly as “in the newspapers” or “in the leaves,” depending on context. The sense is determined by the surrounding words and the intended meaning of lehti in the sentence.
In usage, lehdissä is most common when referring to printed media, such as multiple newspapers. For example,
Grammatically, lehdissä is the plural inessive form, signaling location "in" or "inside" multiple leaves or newspapers.
See also: Finnish grammar, inflection, inessive case, lehti (noun).