Perhaps you should try some spelling variations:
cua phuong » cuu phuong, cuc phuong, luan phuong
hieu sang » chieu sang, hieu lang, hieu quang
doc hieu » toc thieu, hoc thieu, hoc hien
cua nong » cua cong, cuu nong, cua dong
cong san » cong tac
san than » sang than, san thanh, ban than
than cap » khan cap, thanh lap, thanh cac

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: doc hieu sang - canh tranh ((cua phuong) OR (cua nong)) cong san than cap~.
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - canh tranh ((cua phuong) or (cua nong)) cong san than cap*.