Perhaps you should try some spelling variations:
"rurales estudios urbanos." » "locales estudios urbanos.", "morales estudio urbanos.", "reales estudio urbanos."
"reales estudios urbanos." » "reales estudio urbanos.", "locales estudios urbanos.", "leyes estudios urbanos."
"series estudio urbano." » "series estudios urbano.", "serie estudio urbano.", "serie estudios urbano.", "series espacio urbano."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("reales estudios urbanos.") OR ("rurales estudios urbanos."))) or ("series estudio urbano."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("reales estudios urbanos.") OR ("rurales estudios urbanos."))) OR ("series estudio urbano."))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"reales estudios urbanos.\") OR (\"rurales estudios urbanos.\"))) or (\"series estudio urbano.\"))*".
• Removing quotes may allow a broader search: (((( reales estudios urbanos. ) OR ( rurales estudios urbanos. ))) or ( series estudio urbano. ))*.