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