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

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("tres estudios urbanos.") or ("dos estudios hispano."))) or ("series estudios americanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("tres estudios urbanos.") OR ("dos estudios hispano."))) OR ("series estudios americanos.")).
• Removing quotes may allow a broader search: (((( tres estudios urbanos. ) or ( dos estudios hispano. ))) or ( series estudios americanos. )).
• Adding a wildcard symbol may retrieve word variants: (((("tres estudios urbanos.") or ("dos estudios hispano."))) or ("series estudios americanos."))*.