Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nhung tung » nhung tuong, nhung dung, nhung vung
tranh cua » doanh cua
doc hieu » toc thieu, hoc thieu, hoc hien
manh cua » doanh cua, ban cua
ban toan » ban than, van toan, bao toan
bai toan » bai tap

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: doc hieu quang - canh ((tranh cua) OR (manh cua)) nhung tung ((ban toan) OR (bai toan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu quang - canh ((tranh cua) or (manh cua)) nhung tung ((ban toan) OR (bai toan)) cau~".
• Adding a wildcard symbol may retrieve word variants: doc hieu quang - canh ((tranh cua) or (manh cua)) nhung tung ((ban toan) OR (bai toan)) cau*.