Perhaps you should try some spelling variations:
"de factoor" » "de facto", "de facteur", "de factor", "de factors", "de faktor", "de factooor", "de faitoor", "e factoor"
"de factor" » "de facto", "e factor", "dose factor", "de factoor", "de faitor"
"e factoor" » "e factor", "e factors", "e faktor"
"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: (("de fact") OR ((("de factor") OR ((("de factoor") OR ("e factoor")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"de fact\") or (((\"de factor\") or (((\"de factoor\") OR (\"e factoor\"))))))".
• Removing quotes may allow a broader search: (( de fact ) or ((( de factor ) or ((( de factoor ) OR ( e factoor )))))).
• Adding a wildcard symbol may retrieve word variants: (("de fact") or ((("de factor") or ((("de factoor") OR ("e factoor"))))))*.