Perhaps you should try some spelling variations:
"age factor" » "age factors", "male factor", "scale factor"
"e factor" » "e factors"
"one factor" » "one factors"
"de fact" » "de facto", "de fait", "e fact"

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: (((((("e factor") OR ("age factor"))) OR ("one factor"))) OR ("de fact")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"e factor\") OR (\"age factor\"))) or (\"one factor\"))) or (\"de fact\"))".
• Removing quotes may allow a broader search: (((((( e factor ) OR ( age factor ))) or ( one factor ))) or ( de fact )).
• Adding a wildcard symbol may retrieve word variants: (((((("e factor") OR ("age factor"))) or ("one factor"))) or ("de fact"))*.