Perhaps you should try some spelling variations:
de literatura » de litterature, la literatura, a literatura
peer studien » peers studien, peer studie, peer studies
y literatura » la literatura
4 filosofia » e filosofia, a filosofia, y filosofia
best peer » best peere, best peep, best paper
studien 4 » studien _, studien 3, studien 5

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: best peer studien 4 filosofia ((de literatura) OR (y literatura)).
• Adding a wildcard symbol may retrieve word variants: best peer studien 4 filosofia ((de literatura) or (y literatura))*.