Perhaps you should try some spelling variations:
chiet tach » chieu sach
nhieu tang » chieu sang, hieu lang, nhiet nang
hanh trung » thanh trung, hanh trang, manh trung
nhung cong » dung cong, thong cong, hang cong
trung va » truong va, trang va, trung ha
tap toan » tap doan, bai toan
tap quan » tac quan, hai quan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((chiet tach) or (nhieu tang)) - hanh trung va nhung cong ((tap toan) OR (tap quan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chiet tach) OR (nhieu tang)) - hanh trung va nhung cong ((tap toan) OR (tap quan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chiet tach) or (nhieu tang)) - hanh trung va nhung cong ((tap toan) OR (tap quan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((chiet tach) or (nhieu tang)) - hanh trung va nhung cong ((tap toan) OR (tap quan)) cau*.