Perhaps you should try some spelling variations:
chiet tach » chieu sach
tung quang » tuong quang, hung quang, vung quang
dung quang » dang quang, dung quan, luong quang
trong hach » trong mach, trong cach, trong hanh
hieu lang » chieu sang, hieu quang, nhieu tang
hach toan » thanh toan, manh toan
toan ban » van ban

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: doi ((chiet tach) OR (hieu lang)) - thanh ((tung quang) OR (dung quang)) dung trong hach toan ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((chiet tach) or (hieu lang)) - thanh ((tung quang) OR (dung quang)) dung trong hach toan ban~".
• Adding a wildcard symbol may retrieve word variants: doi ((chiet tach) or (hieu lang)) - thanh ((tung quang) OR (dung quang)) dung trong hach toan ban*.