Perhaps you should try some spelling variations:
thanh tung » thanh cong
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
cong ban » cong bang, cong san, cong tan
cong tac » cong ty
than cau » toan cau, phan cau, than cap
tung va » trung va, tuong va, dung va
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: hoc hieu lang - thanh tung va dung ((cong ban) OR (cong tac)) than cau~.
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh tung va dung ((cong ban) or (cong tac)) than cau*.