Perhaps you should try some spelling variations:
"estudios humanisticos en." » "estudios linguisticos en.", "estudios humanisticas en.", "estudios humanistico en.", "estudios humanistica en."
"estudios las especies." » "estudio las especies.", "estudios mas especies.", "estudios a especies.", "estudios de especies."
"estudio la series." » "estudio a series.", "estudio de series.", "estudio en series.", "estudio las series.", "estudio la serie.", "estudio das series."

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: (("estudios humanisticos en.") OR ((("estudios las especies.") OR ("estudio la series."))))~.
• Removing quotes may allow a broader search: (( estudios humanisticos en. ) or ((( estudios las especies. ) or ( estudio la series. ))))~.
• Adding a wildcard symbol may retrieve word variants: (("estudios humanisticos en.") or ((("estudios las especies.") or ("estudio la series."))))*.