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
ban cong » bang cong, phan cong, ban huong
van cong » van dong, van phong, phan cong
tac tren » rac tren, tai tren, tap tren
tren tau » tren thuc, tren may, tren dat
ho hieu » ho chieu, hoi hieu, nho hieu

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