Perhaps you should try some spelling variations:
thieu luat » hieu luat, hien luat, thue luat
quang dat » quang dai, quang dam, quang phat
hieu suat » hieu luat, hieu qua
tinh dang » tinh dung, binh dang, tinh sang
dang hung » dang quang, manh hung, dang cong
hung sach » dung sach, duong sach, chung cach
van hieu » cao hieu
dat van » dao van, dat va, dam van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang dat van hieu suat ) or ( tinh dang hung sach thieu luat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang dat van hieu suat ) OR ( tinh dang hung sach thieu luat ))*.