Perhaps you should try some spelling variations:
models studien » models studies, modell studien, models studied
la literatura » la litterature, a literature
am filosofia » em filosofia, la filosofia, e filosofia
test models » trust models, cost models, testing models
a filosofia » la filosofia, e filosofia, di filosofia

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: test models studien ((am filosofia) OR (a filosofia)) la literatura.
• Adding a wildcard symbol may retrieve word variants: test models studien ((am filosofia) or (a filosofia)) la literatura*.