When searching in the newspaper portal, lemmatisation is used for nouns and proper names. Lemmatisation is the reduction of a word to its basic form, the so-called lemma. For the search in the newspaper portal, this means that a search for "Schillers" will also find "Schiller". So it doesn't matter whether you enter "Schiller" or "Schillers" in the search slot, you will get the same results in both cases. Currently, lemmatisation is also used in the phrase search, i.e. it does not matter whether you search for "Schiller National Museum" or "Schillers National Museum". You can find out more about lemmatisation at Wikipedia, for example: https://en.wikipedia.org/wiki/Lemma_(morphology).