Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
hieu quan » hieu qua, lieu quan, thien quan
tranh cua » doanh cua, manh cua
cua trong » cua truong, cua trung, qua trong
thanh lap » thanh san, phan lap, thanh hai
cong dan » cong san, huong dan, cong dong
cong tan » cong tac, cong san, cong thanh

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

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