Perhaps you should try some spelling variations:
"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 minh khai" » "nguyen thi minh khue", "nguyen thi minh chau", "nguyen thi minh chi", "nguyen thi hanh khai"
"nguyen thi bich khai" » "nguyen thi lich thai", "nguyen thi bich ha", "nguyen thi bien khai"

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