Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
dung cong » dung trong
cong tap » cuong tap, cong tac, cong tan
toan cao » toan tap
toan ban » van ban
tung va » trung va, tuong va, dung va
va dung » van dung, va duong, vat dung

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