Perhaps you should try some spelling variations:
tranh luat » trinh luat, tranh luan, trinh luan
dung thanh » duong thanh, dong thanh, dang thanh
hieu tang » nhieu tang, hieu tieng, kieu trang
hieu lang » chieu sang, hieu quang, nhieu tang
luat dung » suat dung, luat chung, luat quang
dung toan » dung doanh, dung thang, dung tai

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 tang) OR (hieu lang)) - canh tranh luat dung trong ((dung toan) OR (dung thanh)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi ((hieu tang) OR (hieu lang)) - canh tranh luat dung trong ((dung toan) or (dung thanh)) tap~".
• Adding a wildcard symbol may retrieve word variants: hoi ((hieu tang) OR (hieu lang)) - canh tranh luat dung trong ((dung toan) or (dung thanh)) tap*.