Perhaps you should try some spelling variations:
models studies » model studies, modern studies, modeling studies
de litterature » la litterature, et litterature
de literatura » la literatura, y literatura, a literatura
roi models » roi model, coli models, loci models
studies la » studies lab, studies lca, studies lia

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: "roi models studies la filosofia ((de literatura) OR (de litterature))".
• Adding a wildcard symbol may retrieve word variants: roi models studies la filosofia ((de literatura) OR (de litterature))*.