Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
phan cang » phan cong, phan dang, phan cung
cang luat » tang luat, nang suat, tang luan
luat cong » thuat cong, luat chung, cua cong
cong cong » cong dong, trong cong, dung cong
doi hieu » doi chieu, doc hieu, doi hien
cong dan » cong san, cong tan, huong dan
toan cau » toan cao, toan ban, toan tai
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: doi hieu lang - phan cang luat cong cong dan ((toan cau) OR (toan tap))~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - phan cang luat cong cong dan ((toan cau) or (toan tap))*.