Perhaps you should try some spelling variations:
thanh tung » thanh cong
cong thanh » dong thanh, cong trinh, truong thanh
hieu lang » chieu sang, hieu quang, nhieu tang
cong tan » cong tac, cong san, cong ty
toan cao » toan ban, toan tap
ho hieu » ho chieu, hoi hieu, nho hieu
va dung » van dung, va duong, vat dung

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - ((thanh trung) OR (thanh tung)) va dung ((cong thanh) OR (cong tan)) toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - ((thanh trung) or (thanh tung)) va dung ((cong thanh) OR (cong tan)) toan cao~".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - ((thanh trung) or (thanh tung)) va dung ((cong thanh) OR (cong tan)) toan cao*.