Perhaps you should try some spelling variations:
da literatura » la literatura, a literatura, de literatura
filosofia da » filosofia de, filosofia del, filosofia e
test modell » tekst modell, test models, test model
studien aus » studie aus
studien am » studien a, studien auf, studien _

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: "test modell ((studien am) OR (studien aus)) filosofia da literatura".
• Adding a wildcard symbol may retrieve word variants: test modell ((studien am) OR (studien aus)) filosofia da literatura*.