Perhaps you should try some spelling variations:
"de factor" » "de facto", "dose factor", "mode factor", "de factors", "done factor", "dage factor"
"e factor" » "e factors", "one factor", "age factor"
"noise factor" » "noise factors", "noisone factor", "noisage factor"

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: (((("de factor") OR ("e factor"))) OR ("noise factor")).
• Removing quotes may allow a broader search: (((( de factor ) or ( e factor ))) or ( noise factor )).
• Adding a wildcard symbol may retrieve word variants: (((("de factor") or ("e factor"))) or ("noise factor"))*.