Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
hang thong » hang thuong, mang thong, thong thong
hang khong » hang thuong, hang khoa, hang nong
cong thanh » dong thanh, cong trinh, cong tan
thanh khan » thanh phan, thanh nhan, thanh thanh
hieu quan » hieu qua, lieu quan, thien quan
khan cap » khan ap, than cap, khoan cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: thien ((hieu quang) or (hieu quan)) - canh tranh ((hang thong) OR (hang khong)) cong thanh khan cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thien ((hieu quang) OR (hieu quan)) - canh tranh ((hang thong) OR (hang khong)) cong thanh khan cap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thien ((hieu quang) or (hieu quan)) - canh tranh ((hang thong) OR (hang khong)) cong thanh khan cap".
• Adding a wildcard symbol may retrieve word variants: thien ((hieu quang) or (hieu quan)) - canh tranh ((hang thong) OR (hang khong)) cong thanh khan cap*.