Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
doi hieu » doi chieu, doc hieu, doi hien
cua dung » cua dong, qua dung, cua rung
cua dang » cua cong, cua ban
cong san » cong tac
san than » sang than, san thanh, ban than
than cau » toan cau, phan cau, than cap

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 - canh tranh ((cua dung) or (cua dang)) cong san than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - canh tranh ((cua dung) OR (cua dang)) cong san than cau.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - canh tranh ((cua dung) or (cua dang)) cong san than cau*.