Perhaps you should try some spelling variations:
"vietnamese americans" » "vietnamese americanns", "vietnam's americanns", "vietnamese curriculans"
"vietnamese america" » "vietnamese american", "vietnam's american", "vietnamese curricula"
"vietnam american" » "vietnam's american", "vietnamese american", "vietnam bayesian"

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: (("vietnamese americans") OR ((("vietnamese america") OR ("vietnam american")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"vietnamese americans\") or (((\"vietnamese america\") OR (\"vietnam american\"))))".
• Removing quotes may allow a broader search: (( vietnamese americans ) or ((( vietnamese america ) OR ( vietnam american )))).
• Adding a wildcard symbol may retrieve word variants: (("vietnamese americans") or ((("vietnamese america") OR ("vietnam american"))))*.