Perhaps you should try some spelling variations:
"de facteur" » "de facteurs", "le facteur", "du facteur"
"de factor" » "de facto", "e factor", "dose factor"
"de facts" » "de facto", "de faits", "cbe facts"
"de factr" » "de facto", "de fazer", "de facon"

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