Perhaps you should try some spelling variations:
"tres estudios hispanic." » "tres estudios hispanicos.", "tres estudios hispano.", "tres studies hispanic.", "otros estudios hispanic.", "los estudios hispanic.", "dos estudios hispanic."
"dios estudios urbano." » "dios estudios urbanos.", "dios estudio urbano.", "dios estudios peruanos.", "dos estudios urbano.", "los estudios urbano.", "otros estudios urbano."
"series estudios urbano." » "series estudios urbanos.", "series estudio urbano.", "series estudios peruanos.", "serie estudios urbano.", "seis estudios urbano.", "leyes estudios urbano."

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: (((("dios estudios urbano.") or ("series estudios urbano."))) or ("tres estudios hispanic."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dios estudios urbano.") OR ("series estudios urbano."))) OR ("tres estudios hispanic.")).
• Removing quotes may allow a broader search: (((( dios estudios urbano. ) or ( series estudios urbano. ))) or ( tres estudios hispanic. )).
• Adding a wildcard symbol may retrieve word variants: (((("dios estudios urbano.") or ("series estudios urbano."))) or ("tres estudios hispanic."))*.