Perhaps you should try some spelling variations:
model studien » modell studien, model studies, models studies
da literatura » la literatura, a literatura, de literatura
am filosofia » em filosofia, la filosofia, e filosofia
a filosofia » la filosofia, e filosofia, di filosofia
test model » test models, trust model, cost model

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 model studien ((am filosofia) OR (a filosofia)) da literatura*".