Perhaps you should try some spelling variations:
quan nhung » qua nhung, cua nhung, luan chung
hieu lang » chieu sang, hieu quang, nhieu tang
ganh nang » anh nang, nganh nong, van nang
nang quan » ban quan, nang suat
doi hieu » doi chieu, doc hieu, doi hien
cong san » cong tac
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 - ganh nang quan nhung ((cong san) OR (huong dan)) ((toan cau) OR (toan tap))~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - ganh nang quan nhung ((cong san) or (huong dan)) ((toan cau) or (toan tap))*.