Perhaps you should try some spelling variations:
"than vinh van tinh hoc." » "thanh vinh van tinh hoc.", "than kinh van tinh hoc.", "tran vinh van tinh hoc.", "than vinh van thinh hoc.", "than vinh van minh hoc.", "than vinh ban tinh hoc.", "than dinh van tinh hoc.", "than trinh van tinh hoc.", "than sinh vat tinh hoc.", "than vinh van sinh hoc.", "than vinh van tin hoc.", "than vinh van hinh hoc."
"thi hinh van tinh duc." » "thi hanh van tinh duc.", "thi minh van tinh duc.", "thi thanh van tinh duc.", "thi dinh van tinh duc.", "thi hinh va tinh duc.", "thi binh van tinh duc.", "thi hinh van thinh duc.", "thi hinh van minh duc.", "thi hinh ban tinh duc.", "thi hinh van dinh duc.", "thi hinh van ninh duc."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("thi hinh van tinh duc.") or ("than vinh van tinh hoc."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("thi hinh van tinh duc.") OR ("than vinh van tinh hoc.")).
• Removing quotes may allow a broader search: (( thi hinh van tinh duc. ) or ( than vinh van tinh hoc. )).
• Adding a wildcard symbol may retrieve word variants: (("thi hinh van tinh duc.") or ("than vinh van tinh hoc."))*.