Perhaps you should try some spelling variations:
canh thanh » canh tranh, danh thanh, anh thanh
viet tach » viet sach, viet thanh, chiet tach
viet tech » viet sach
thanh qua » thanh quan, thanh qui, hanh qua
cong manh » cong danh, duong manh, cong thanh
duong van » duong va, luong va, dang van
qua dung » quang dung, su dung, qua song
toan tap » toan ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((viet tach) OR (viet tech)) - canh thanh qua dung ((cong manh) or (duong van)) toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((viet tach) OR (viet tech)) - canh thanh qua dung ((cong manh) OR (duong van)) toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((viet tach) OR (viet tech)) - canh thanh qua dung ((cong manh) or (duong van)) toan tap".
• Adding a wildcard symbol may retrieve word variants: doi ((viet tach) OR (viet tech)) - canh thanh qua dung ((cong manh) or (duong van)) toan tap*.