Perhaps you should try some spelling variations:
del letterature » e letterature, le letterature, della letteratura
de litterature » la litterature, et litterature
werte oder » werte der
studie y » studie _, studie 1, studie 3

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: werte oder ((studie y) OR (studie 2)) filosofia ((del letterature) OR (de litterature)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "werte oder ((studie y) or (studie 2)) filosofia ((del letterature) OR (de litterature))".
• Adding a wildcard symbol may retrieve word variants: werte oder ((studie y) or (studie 2)) filosofia ((del letterature) OR (de litterature))*.