Perhaps you should try some spelling variations:
thanh duong » thanh huong, thanh cuong, thanh vuong
hieu lang » chieu sang, hieu quang, nhieu tang
doi hieu » doi chieu, doc hieu, doi hien
duong va » duong van, dung va, luong va
cong tac » cong ty
than cau » toan cau, phan cau, than cap
va tong » va thong, va tuong, va trong

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi hieu lang - thanh duong va tong ((cong san) or (cong tac)) than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - thanh duong va tong ((cong san) OR (cong tac)) than cau.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - thanh duong va tong ((cong san) or (cong tac)) than cau*.