Perhaps you should try some spelling variations:
del literatur » model literatur, teil literatur, igel literatur
de filosofia » e filosofia, di filosofia, la filosofia
belt scale » belt scales, belt stable, belt case
set scale » sets scale, best scale, rest scale
study de » study die, study der, study dem

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: "((set scale) OR (belt scale)) study de filosofia del literatur".
• Adding a wildcard symbol may retrieve word variants: ((set scale) OR (belt scale)) study de filosofia del literatur*.