Perhaps you should try some spelling variations:
"jon duncan sarah" » "jon duncan adam", "jon duncan gray", "jon duncan shaw", "j duncan sarah", "ian duncan sarah", "colin duncan sarah"
"john duncan sarah" » "john duncan adam", "john duncan gray", "john duncan shaw", "john dunton sarah", "john dunning sarah"
"brian duncan m" » "ian duncan m", "bruce duncan m", "brian duncan _", "brian duncan m.d"

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: (((("jon duncan sarah") OR ("john duncan sarah"))) OR ("brian duncan m")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"jon duncan sarah\") OR (\"john duncan sarah\"))) or (\"brian duncan m\"))".
• Removing quotes may allow a broader search: (((( jon duncan sarah ) OR ( john duncan sarah ))) or ( brian duncan m )).
• Adding a wildcard symbol may retrieve word variants: (((("jon duncan sarah") OR ("john duncan sarah"))) or ("brian duncan m"))*.