Perhaps you should try some spelling variations:
safety studien » safety studies, safety study, safety stories
stents safety » agents safety, events safety, tenth safety
die filosofia » di filosofia, de filosofia, e filosofia
a literatura » la literatura, y literatura, a literatur
studien die » studie die, studien der

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 die filosofia ((a literatura) OR (a literature))*".