Perhaps you should try some spelling variations:
de literatura » de litterature, la literatura, y literatura
e literatura » y literatura, e literatur, a literatura
belt scales » belt scale, belt scars, about scales
studien l » studien 3, studien 4, 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: belt scales ((studien l) OR (studien _)) filosofia ((e literatura) OR (de literatura)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "belt scales ((studien l) or (studien _)) filosofia ((e literatura) OR (de literatura))".
• Adding a wildcard symbol may retrieve word variants: belt scales ((studien l) or (studien _)) filosofia ((e literatura) OR (de literatura))*.