Perhaps you should try some spelling variations:
e investigaciones » de investigaciones, e investigacion, las investigaciones
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: ((peru estudios) or (series studies)) e investigaciones.