Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
hieu quang » thieu quang, hieu quan, hieu qua
dung cuong » dung cong, dung luong, dang cuong
cuong tap » luong tap, cong tac, luong tai
trung va » truong va, trang va, trung ha
tap quan » tac quan, hai quan
quan cao » quang cao, quan cau, quan ao
tung va » tuong va, dung va, vung va

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 ((chieu sach) OR (hieu quang)) - thanh ((tung va) OR (trung va)) dung cuong tap quan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu sach) or (hieu quang)) - thanh ((tung va) OR (trung va)) dung cuong tap quan cao~".
• Adding a wildcard symbol may retrieve word variants: ho ((chieu sach) or (hieu quang)) - thanh ((tung va) OR (trung va)) dung cuong tap quan cao*.