Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu sang, chieu tinh
thanh dung » thanh duong, thanh tung, thanh hung
hieu lang » chieu sang, hieu quang, nhieu tang
dung cong » dung trong
tap toan » tap doan, tap quan
bai toan » bai tap
va dung » van dung, va duong, vat dung

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ho ((chieu xanh) or (hieu lang)) - thanh dung va dung cong ((tap toan) OR (bai toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu xanh) OR (hieu lang)) - thanh dung va dung cong ((tap toan) OR (bai toan)) cao*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu xanh) or (hieu lang)) - thanh dung va dung cong ((tap toan) OR (bai toan)) cao*".