Perhaps you should try some spelling variations:
"factores politicos" » "actos politicos", "factores biologicos", "factores climaticos"
"valores politicos" » "valores eticos"
"factos politicos" » "actos politicos", "efectos politicos", "impactos politicos"
"factores criticos" » "factores critico", "factores critica", "factores critical"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((((("factores politicos") OR ("factos politicos"))) or ((("actores politicos") or ("valores politicos"))))) or ("factores criticos"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((((("factores politicos") OR ("factos politicos"))) OR ((("actores politicos") OR ("valores politicos"))))) OR ("factores criticos")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"factores politicos\") OR (\"factos politicos\"))) or (((\"actores politicos\") or (\"valores politicos\"))))) or (\"factores criticos\"))".
• Removing quotes may allow a broader search: (((((( factores politicos ) OR ( factos politicos ))) or ((( actores politicos ) or ( valores politicos ))))) or ( factores criticos )).
• Adding a wildcard symbol may retrieve word variants: (((((("factores politicos") OR ("factos politicos"))) or ((("actores politicos") or ("valores politicos"))))) or ("factores criticos"))*.