Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu tinh, hieu manh
chieu sang » chieu sach, hieu lang, nhieu tang
quang dung » quang trung, ung dung, cuong dung
canh tinh » hanh tinh, manh tinh, canh tranh
dung cong » dung trong
tap toan » tap quan, bai toan
tap doan » tap quan

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: theo ((chieu xanh) OR (chieu sang)) - canh tinh quang dung cong ((tap toan) OR (tap doan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((chieu xanh) OR (chieu sang)) - canh tinh quang dung cong ((tap toan) or (tap doan)) cau~".
• Adding a wildcard symbol may retrieve word variants: theo ((chieu xanh) OR (chieu sang)) - canh tinh quang dung cong ((tap toan) or (tap doan)) cau*.