Perhaps you should try some spelling variations:
stents safety » agents safety, events safety, tenth safety
da literatura » la literatura, a literatura, de literatura
filosofia da » filosofia de, filosofia del, filosofia e
studien am » studien aus, studien auf, studien _
studien a » studien _, studien 3, studien 4

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "stents safety ((studien a) OR (studien am)) filosofia da literatura*".