Perhaps you should try some spelling variations:
"seis estudios americanos." » "seis estudios latinoamericanos.", "los estudios americanos.", "dos estudios americanos.", "dios estudios americanos."
"series estudios urbano." » "tres estudios urbano.", "leyes estudios urbano.", "sociales estudios urbano.", "series estudios urbanos.", "series estudio urbano.", "series estudios peruanos."
"serie estudios urbano." » "serie estudios urbanos.", "serie estudio urbano.", "serie estudios peruanos."

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