Perhaps you should try some spelling variations:
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
tranh va » tranh van, trang va, trinh va
cong dan » huong dan, cong dong, cong tac
cong tan » cong tac, cong thanh, cong ty
cong san » cong tac
toan tap » toan ban

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: theo hieu lang - canh tranh va nhung ((((cong dan) OR (cong tan))) OR (cong san)) toan tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - canh tranh va nhung ((((cong dan) OR (cong tan))) or (cong san)) toan tap~".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - canh tranh va nhung ((((cong dan) OR (cong tan))) or (cong san)) toan tap*.