Perhaps you should try some spelling variations:
"nguyen thi thanh khai" » "nguyen thi thanh hai", "nguyen thi than khai", "nguyen thi thanh phan", "nguyen thi tmanh khai", "nguyen thi tnhanh thai", "nguyen thi tthanh hai"
"nguyen chi minh khai" » "nguyen can minh khai", "nguyen nhu minh khai", "nguyen hai minh khai", "nguyen chi minh khue", "nguyen chi minh chau", "nguyen chi minh chi"
"nguyen thi hanh khai" » "nguyen thi manh khai", "nguyen thi nhanh thai", "nguyen thi thanh hai"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("nguyen chi minh khai") or ((("nguyen thi hanh khai") OR ("nguyen thi thanh khai"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("nguyen chi minh khai") OR ((("nguyen thi hanh khai") OR ("nguyen thi thanh khai")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"nguyen chi minh khai\") or (((\"nguyen thi hanh khai\") OR (\"nguyen thi thanh khai\"))))".
• Removing quotes may allow a broader search: (( nguyen chi minh khai ) or ((( nguyen thi hanh khai ) OR ( nguyen thi thanh khai )))).
• Adding a wildcard symbol may retrieve word variants: (("nguyen chi minh khai") or ((("nguyen thi hanh khai") OR ("nguyen thi thanh khai"))))*.