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

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