Perhaps you should try some spelling variations:
"series estudios urbanos." » "serie estudios urbanos.", "seis estudios urbanos.", "leyes estudios urbanos."
"seire estudio urbano." » "seire estudios urbano.", "seire espacio urbano.", "serie estudio urbano.", "sangre estudio urbano."
"tres estudios hispano." » "otros estudios hispano.", "los estudios hispano.", "dos estudios hispano.", "tres estudios hispana.", "tres estudios hispanic."

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

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