Perhaps you should try some spelling variations:
las investigaciones » la investigacion, de investigaciones, las instituciones
series studies » species studies, sers studies, studies studies
peru estudios » para estudios, peru studies, de estudios

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Removing quotes may allow a broader search: ((series studies) or (peru estudios)) las investigaciones.