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 hanh khai" » "nguyen thi nhanh thai", "nguyen thi thanh hai", "nguyen thi dang khai", "nguyen thi thanh khai"
"nguyen thi manh khai" » "nguyen thi manh hai", "nguyen thi dang khai", "nguyen thi lanh hai", "nguyen thi minh khai", "nguyen thi anh khai", "nguyen thi oanh 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 hanh khai") OR ("nguyen thi manh 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 manh 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 manh khai\"))))".
• Removing quotes may allow a broader search: (( nguyen chi minh khai ) or ((( nguyen thi hanh khai ) OR ( nguyen thi manh khai )))).
• Adding a wildcard symbol may retrieve word variants: (("nguyen chi minh khai") or ((("nguyen thi hanh khai") OR ("nguyen thi manh khai"))))*.