Perhaps you should try some spelling variations:
"otros estudios peruanoss." » "otros estudios peruanos.", "otros estudios urbanos.", "los estudios peruanoss.", "dos estudios peruanoss.", "etnicos estudios peruanoss."
"seis estudios peruanoss." » "seis estudios peruanos.", "seis estudios urbanos.", "los estudios peruanoss.", "dos estudios peruanoss.", "dios estudios peruanoss."
"series estudio urbano." » "series estudios urbano.", "serie estudio urbano.", "serie estudios urbano.", "series estudios urbanos.", "series espacio urbano."

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