Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
trinh qua » trinh quan, trinh quang, trinh luat
trinh cua » tinh cua, trinh luat, trinh quan
bang cong » bang song, hang cong, dung cong
dang cong » dung cong
nho hieu » nha hieu, nho sieu, nhu hieu
tac tren » rac tren, tai tren, tap tren
tren tau » tren thuc, tren may, tren dat

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: nho hieu quang - hanh ((trinh qua) OR (trinh cua)) ((bang cong) OR (dang cong)) tac tren tau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "nho hieu quang - hanh ((trinh qua) or (trinh cua)) ((bang cong) OR (dang cong)) tac tren tau~".
• Adding a wildcard symbol may retrieve word variants: nho hieu quang - hanh ((trinh qua) or (trinh cua)) ((bang cong) OR (dang cong)) tac tren tau*.