Perhaps you should try some spelling variations:
inmigracion extranjera » inversion extranjera (Expand Search)
percepciones de » percepcion de (Expand Search), concepciones de (Expand Search), percepcion del (Expand Search)
la inmigracion » la integracion (Expand Search)
de actitudes » y actitudes (Expand Search), las actitudes (Expand Search)
hacia la » hacia una (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: parametro : percepciones de actitudes hacia la inmigracion extranjera~.
• Adding a wildcard symbol may retrieve word variants: parametro : percepciones de actitudes hacia la inmigracion extranjera*.