Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
tranh cua » doanh cua, manh cua
dung cong » dung trong
hoi hieu » hoi phieu, hoi tieu, moi hieu
cua dung » cua dang, cua dong, qua dung
cong dan » cong san, cong tan, huong dan
toan cao » toan ban
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: hoi hieu lang - canh tranh cua dung cong dan ((toan cao) OR (toan tap))~.
• Adding a wildcard symbol may retrieve word variants: hoi hieu lang - canh tranh cua dung cong dan ((toan cao) or (toan tap))*.