Perhaps you should try some spelling variations:
models studies » model studies, modern studies, modeling studies
la literatura » la litterature, a literature
e literatura » de literatura, y literatura, e literatur
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: roi models studies la filosofia ((e literatura) OR (la literatura)).
• Adding a wildcard symbol may retrieve word variants: roi models studies la filosofia ((e literatura) or (la literatura))*.