Perhaps you should try some spelling variations:
"seis estudios urbano." » "seis estudio urbano.", "seis estudios peruanos.", "seis estudios hispano.", "los estudios urbano.", "dios estudios urbano.", "pons estudios urbano."
"dos estudios urbanos." » "dos estudio urbanos.", "dos estudios peruanoss.", "dos estudios hispanos.", "los estudios urbanos."
"serie studia urbano." » "serie estudio urbano.", "serie estudios urbano."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("serie studia urbano.") or ((("seis estudios urbano.") or ("dos estudios urbanos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("serie studia urbano.") OR ((("seis estudios urbano.") OR ("dos estudios urbanos."))))*.
• Removing quotes may allow a broader search: (( serie studia urbano. ) or ((( seis estudios urbano. ) or ( dos estudios urbanos. ))))*.