Perhaps you should try some spelling variations:
na literatura » la literatura, a literatura, a literature
filosofia na » filosofia da, filosofia la, filosofia n
burst scale » bast scale, best scale, just scale
studien bei » studie bei
studien es » studien aus, studien ein, studien als

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

• If you are trying to use Boolean operators, they must be ALL CAPS: burst scale ((studien es) OR (studien bei)) filosofia na literatura*.